College of Arts and Sciences

Flat bands, topology, and fractionalization — a new pathway towards fractional topological states
 
Kai Sun
 
Department of Physics, University of Michigan
 
In many-body quantum systems, it has long been known that the interplay of nontrivial topology and strong interactions can lead to the emergence of intriguing phenomena that transcend standard doctrines. One such phenomenon is fractionalization, where excitations in a many-body system become “smaller” than the smallest building block of the system, carrying fractional charge or exhibiting fractional statistics. Although these theoretical concepts and principles were developed decades ago, the realization of fractional topological states remains sparse.

Continue reading… Kai Sun (University of Michigan) – Special date & time!

Biomolecular Condensation Enables Material State Changes that Dynamically Regulate RNA Metabolism 

Recently, biomolecular condensates have emerged as a broadly utilized mechanism for organizing biochemical pathways within cells, and this organizational paradigm is particularly important within bacteria because these organisms generally lack membrane-bound organelles. Bacterial ribonucleoprotein bodies (BR-bodies) are dynamic biomolecular condensates that play a pivotal role in bacterial RNA metabolism. In this talk, I will demonstrate how BR-bodies orchestrate mRNA decay and storage based on a multidisciplinary approach that combines single-molecule fluorescence microscopy, bulk imaging techniques, biochemical assays, and rigorous quantitative analyses. During exponential growth, BR-bodies act as fluid-like condensates that enhance mRNA decay.

Continue reading… Luis Ortiz-Rodriguez (University of Michigan)

Beyond Quantum Mechanics

We formulated an alternative to quantum mechanics, whose basic starting point is pure information represented by binary sequences, without any reference to space, time and matter. Directly from these binary sequences, we derived highly non-trivial QM results: rules of angular momentum addition, quantum harmonic oscillator, Clebsch-Gordan coefficients and Wigner’s d-matrix formula. In particular, Wigner’s formula can be used to describe experiments with two sequential Stern-Gerlach detectors relatively rotated by some angle (which actually represents the first step toward formulating an emergent quantum spacetime). Being inherently discrete, and matching most of the quantum mechanical predictions only in the continuum limit where the length of the sequences is infinite,

Continue reading… Dejan Stojkovic (U Buffalo)

Transforming the Landscape of Photonics with Liquid Metals

Metals are widely used in various electronic and photonic devices for different purposes. Conventional
metals such as gold, aluminum and copper are all solid metals, which lack structural reconfigurability and
are prone to structural damage upon repeated deformation such as bending and stretching. In recent years,
room temperature liquid metals including gallium and gallium-rich alloys have been exploited to develop
soft, stretchable and reconfigurable electronics. The rising tide of liquid metals is also lifting the
photonics boat and ushering in new possibilities. Liquid metals have been utilized to realize
reconfigurable RF antennas and plasmonic structures in the visible and UV spectral regions,

Continue reading… Peter Qiang Liu (University at Buffalo)

Exotic Higgs decays & AI triggers at the LHC

Data at the LHC allows us to probe whether the Higgs boson communicates with unknown and/or undiscovered sectors beyond the Standard Model. I will discuss ATLAS results on the searches for Higgs decays to dark matter candidates [2202.07953, 2109.00925] as well as MC studies of exotic Higgs decays to pseudoscalars in the 4b [2306.01901] and 2γ2b final states. I will also describe the technical challenges of triggering on such events using missing energy and/or jets, including novel approaches to ML in real-time FPGA-based trigger systems [2104.03408, 2207.05602, 2409.20506], including unsupervised AI via anomaly detection using decision-tree-based autoencoders [2304.03836].

Continue reading… Tae Min Hong (U Pittsburgh)

Continue reading… No seminar (faculty meeting)

Low-Temperature Reaction Kinetics Tools for Quantum-State-Resolved Chemistry

Many laboratory methodologies have grown out of developments in the field of atomic, molecular, and optical physics that are ripe for breakthrough studies in the hands of physical chemists. Exquisite control over quantum-state populations now enables chemical reactions to be studied to a level of detail not previously attainable. In this talk, I will describe how we have adopted buffer-gas-cooling (sympathetic/collisional cooling) techniques along with radiofrequency ion traps to investigate chemical reactions that depend sensitively on the initial quantum state of the reactants.

I will describe our work to measure reaction rate constants for radiative-association reactions,

Continue reading… Leah Dodson (University of Maryland, Chemistry and Biochemistry)

Rapid, Hyperparameter-free Point Pattern Analysis of Single Molecule Localizations in 3D using Voronoi Tessellation-Based Clustering

Growing evidence indicates that cardiac biology and physiology at cellular through organ scales are governed by the action of proteins organized within nanodomains with specialized ultrastructural properties. Multiple phenomena have been identified, whose function and dysfunction cannot be predicted without accounting for the makeup and behavior of nanodomains. Thus, my laboratory’s investigative approach is grounded in high resolution structural and functional imaging, complemented by our development of novel imaging and image analysis approaches. I will present work illustrating how super-resolution microscopy and quantitative image analysis have enabled us to make inroads into cardiac physiology,

Continue reading… Rengasayee Veeraraghavan – Ohio State

Stream Members Only: Data-Driven Characterization of Stellar Streams for Inference on the Galactic Potential

Our galaxy, the Milky Way, contains a variety of stellar structures whose dynamics are wonderfully sensitive to the matter distribution of the Galaxy.  Among these structures are stellar streams – remnants of smaller galaxies and star clusters disrupted by the Milky Way’s gravitational pull.  By modeling these streams, we can infer details about the underlying gravitational field, giving insight into the distribution and properties of dark matter.  This talk presents a new approach, combining work building new methods to characterize stellar streams, with new computational modeling tools,

Continue reading… Nathaniel Starkman (MIT)

Title: Johnson noise thermometry using ohmic and hydrodynamic electrons

Brian Skinner

Department of Physics, the Ohio State University

Abstract:

Current through a resistor exhibits temperature-dependent white noise fluctuations called Johnson-Nyquist noise. For a 2D electron system, measuring the magnitude of these fluctuations provides a direct measurement of the electron temperature and enables methods for inferring specific heat and thermal conductivity. Here I show how to understand Johnson noise both for electrons whose flow is dictated by Ohm’s law and for electrons whose flow is hydrodynamic. I then discuss experimental results from the group of Philip Kim,

Continue reading… Brian Skinner (Ohio State University)

Tracing orbits and measuring dark matter with stellar and dynamical invariants

Dynamical times in the Milky Way are measured in units of tens of millions of years; how will we ever see an orbit? The surface abundances (element abundances) of a star are (nearly) invariant quantities, as are the dynamical actions in any integrable potential. We combine these ideas with Orbital Torus Imaging, a new way to precisely measure stellar orbits from kinematic and abundance data. We are using data from the SDSS APOGEE and ESA Gaia instruments to measure the acceleration field and dark matter distribution in the Milky Way.

Continue reading… David Hogg (New York University)

Title: CMOS and EUV Nanophotonics
 
Mohamed ElKabbash
 
Wyant College of Optical Sciences, University of Arizona
 
Abstract: Nanophotonics is an interdisciplinary field that combines science and engineering to explore the behavior of light and its interactions with matter at the nanometer scale. In this talk, I will present our recent work in two new research areas: integrating nanophotonic devices into existing CMOS foundry processes (CMOS Nanophotonics), and developing novel optical elements for extreme ultraviolet (EUV) wavelengths (EUV Nanophotonics).

First, I will discuss our advancements in CMOS Nanophotonics, where we fabricate and integrate nanophotonic devices within established CMOS manufacturing processes.

Continue reading… Mohamed ElKabbash (University of Arizona)

Continue reading… No seminar (Fall Break)

Seeing with the Rainbow: Hyperspectral Remote Sensing with SPHEREx and CubeSounder

Advances in sensor technologies continue to improve the capabilities of passive remote sensing systems to image and characterize the world around us, and in smaller size/weight/power/cost (SWaP-C) envelopes that bring these capabilities to new platforms. In this talk, I will discuss SPHEREx and CubeSounder, two new sensor systems in development at ASU. SPHEREx is a NASA infrared satellite with a wide range of key science goals, including precision mapping of the three-dimensional distribution of galaxies to probe the physics of cosmic inflation. At ASU I am leading a team developing an optimal scheduling system that enables SPHEREx to survey the entire sky while efficiently operating within the challenging operational constraints of LEO.

Continue reading… Sean Bryan (Arizona State University)

Proper time path integrals for gravitational waves

An intriguing aspect of gravitational wave lensing is the emergence wave-effects: interference and diffraction patterns in the waveforms due to finite size effects, occurring when the wave’s wavelength is comparable to the Schwarzschild radius of the lens. These phenomena are particularly interesting because they induce frequency dependent modifications in the waveforms, allowing for a better lens’ parameter estimation, especially if the lensing event has an electromagnetic counterpart in the opposite optical regime.
Despite the promising potential of wave-optics effects, our current theoretical tools, based on the diffraction integral, rely on two main assumptions that limit their effectiveness: the eikonal and paraxial approximations on one hand,

Continue reading… Alice Garoffolo (UPenn)

 
A solid-state platform for cooperative quantum phenomena
 
Benedetta Flebus, 
 
Department of Physics, Boston College
 
 
The dissipation resulting from the coupling of a system with its environment is commonly viewed as a foe for quantum technologies. Nonetheless, recent developments at light-matter interfaces have shown that correlated dissipation can be harnessed into novel dynamical states of matter and
entanglement in many-body quantum systems. In this talk, I will discuss how we have recently capitalized on this knowledge from quantum optics to set the stage for the — yet uncharted — exploration of cooperative quantum phenomena in quantum hybrid solid-state platforms.

Continue reading… Benedetta Flebus (Boston College)

Microwave Cosmology at Large Angular Scales

The Cosmic Microwave Background (CMB), in both temperature and polarization, has provided precise measurements of the Dark Energy + Cold Dark Matter (LCDM) model of cosmology. Numerous ground-based, balloon-borne, and space experiments have extracted most of the available information from the CMB. However, two of the seven possible parameters remain poorly constrained: the tensor-to-scalar ratio ( r ), which parameterizes the amplitude of primordial gravitational waves expected if the Universe underwent early inflation, and Tau ($\tau$), the optical depth to the Epoch of Reionization, which is strongly dependent on the yet unknown mechanism that reionized neutral hydrogen.

Continue reading… Ivan Padilla (Case Western Reserve University)

TBA

Continue reading… Xing Wu (Michigan State)

Thinking about sinking: the settling of shaped solids

The gravitational settling of particles in a viscous fluid is a common process in nature and in industrial contexts.  This familiar process is a confounding problem in many-body physics due to the long-range, directional interactions between sinking particles.  After discussing some known facts and known puzzles in the field, I will present results that show qualitatively new behaviour when the particles have non-trivial shape and orientational degrees of freedom, as do snowflakes, plankton, crystals, and other natural sediment. As examples of the richness that emerges from shape, I will discuss unusual phenomena in the sedimentation of individual polar and polygonal objects,

Continue reading… Narayanan Menon (University of Massachusetts, Amherst)

TBA. 

Host: Shulei Zhang

Continue reading… Kai Sun (University of Michigan) – Rescheduled

SuperBIT: Galaxy Cluster Weak Lensing from a Balloon

SuperBIT is the first of its kind, three-axis stabilized, high-resolution, wide-field imaging telescope that flies on a stratospheric balloon. I report on SuperBIT’s 40-day science flight in 2023, during which it observed dozens of astrophysical targets. Most of the observed targets are galaxy clusters, to study the properties of dark matter in and around the clusters using weak gravitational lensing. All images will be released to the public. SuperBIT observes at wavelngth bands from 300 to 1000 nm with a resolution of 0.35 arcseconds FWHM from its 0.5 m primary aperture.

Continue reading… Steve Benton (Princeton)

Open Quantum Systems: A new frontier of many-body physics

Ahana Chakraborty

Department of Physics and Astronomy, Rutgers University

Join Zoom meeting: 

https://cwru.zoom.us/j/99054239108?pwd=soEzyUCYd80fojLzSuBmPA3Ow9lquc.1

Abstract: The open quantum system (OQS) represents a novel platform of many-body physics,
allowing a quantum system to interact with an external observer or exchange energy and
particles with its environment. Understanding the non-unitary dynamics of OQS is crucial for
addressing fundamental questions in statistical physics, such as thermalization, the approach
to non-thermal steady states, and the generation of quantum entanglement.

Continue reading… Ahana Chakraborty (Rutgers University)

Title: The Ground State of Geometrically Frustrated Magnets
 
Arthur Ramirez
 
Physics Department, University of California, Santa Cruz
 
Join Zoom Meeting:
https://cwru.zoom.us/j/99054239108?pwd=soEzyUCYd80fojLzSuBmPA3Ow9lquc.1
 
 
Abstract: Geometrically frustrated magnets undergo long-range ordering at temperatures far below the mean-field estimate. Such a suppression of ordering has made these materials candidates for the so-called quantum spin liquid, a theoretically predicted fully quantum-coherent state that can admit anyon excitations with their attendant quantum computing potential. I will argue that the ground state emerging in all geometrically frustrated situations is,

Continue reading… Arthur Ramirez (UC Santa Cruz)

TBA

Continue reading… Joe Lesnefsky (Arizona State)

Continue reading… No seminar (Labor Day)

TBA. 

Pino Strangi

Continue reading… Mohamed ElKabbash (U Arizona) – POSTPONED

AI guided discovery of two-dimensional magnetic materials

Trevor David Rhone

Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute

Abstract: The discovery of van der Waals (vdW) materials with intrinsic magnetic order in 2017 has given rise to new avenues for the study of emergent phenomena in two dimensions. In particular, monolayer CrI3 was found to be ferromagnet. Other vdW transition metal halides were later found to have different magnetic properties. How many vdW magnetic materials exist in nature? What are their properties? How do these properties change with the number of layers?

Continue reading… Trevor Rhone (RPI) – Pls note the special time and location

Single-molecule mechanical studies of unstable protein building blocks

The most abundant protein on earth, collagen, is the material building block that forms the basis of our connective tissues and the extracellular matrix that surrounds our cells. It performs important structural and mechanical roles, holding our bodies together and helping our tissues to withstand a wide variety of forces. Surprisingly, collagen proteins are structurally unstable at body temperature.

In this talk, which will be aimed at a very general Physics audience, I will introduce some of the fascinating physical properties of the unique triple-helix structure of collagen and will describe how we are using the techniques of atomic force microscopy and centrifuge force microscopy to study these properties,

Continue reading… Nancy Forde (Simon Fraser University)

The Penrose tiling is a quantum error correcting code

Abstract: I will begin by introducing Penrose tilings (“PTs”) and quantum error correcting codes (“QECCs”).  A PT is a remarkable, intrinsically non-periodic way of tiling the plane whose many beautiful and unexpected properties have fascinated physicists, mathematicians, and geometry lovers of all sorts, ever since its discovery in the 1970s.  A QECC is a fundamental way of protecting quantum information from noise, by encoding the information with a sophisticated type of redundancy.  Such codes play an increasingly important role in physics: in quantum computing (where they protect the delicate quantum state of the computer);

Continue reading… Latham Boyle (University of Edinburgh)

Title: Nonlinear response of disordered superconductors: Higgs amplitude mode under the light
 
Maxim Dzero
 
Department of Physics, Kent State University
 
Abstract: In the past decade there have been an impressive progress made in studying conventional and unconventional superconductors using a pump-probe setup of the terahertz field experiments. In my talk I will first provide an overview of the state-of-the-art experimental techniques. I will proceed with the overview of the theoretical results on the problem of far-from-equilibrium superconductivity which pre-dated the recent experiments. Then I plan to discuss how experimental discoveries motivated the theorists to revisit now classical problems which remained unresolved for many years.

Continue reading… Maxim Dzero (Kent State)

Introduction to HEPfit and its potential to constrain the SMEFT 
 
Abstract: New physics extensions usually include many parameters that can be tuned to be compatible with current data. In many cases, instead of ruling out the models, we are just able to find constraints on their parameters. Finding these constraints, including as much information as possible, is usually challenging due to the huge amount of measurements available. In this seminar, we will show how the package HEPfit can be used to perform these global fits. As a relevant example, we will demonstrate how HEPfit can be used to constrain ‘model agnostic’

Continue reading… Victor Miralles (U Manchester)

Exploring Catalytic Potential: Novel Applications and Post-Processing Methods for LiCoO2

Alp Sehirlioglu

Department of Materials Science and Engineering
Case Western Reserve University

Abstract: LiCoO2 (LCO) serves as a typical cathode material in Li-ion batteries, containing lithium and cobalt, both acknowledged for their potential toxicity. The primary focus in repurposing LCO lies in catalysis, particularly in decomposing environmental pollutants. Previous attempts in utilizing LCO for photocatalysis, electrocatalysis, and thermocatalysis have shown promising results. LCO’s layered structure facilitates delithiation and intercalation, crucial processes in chemical exfoliation. This exfoliation process involves protonation and intercalation,

Continue reading… Alp Sehirlioglu (MSE CWRU)

Fundamental Symmetries in Nuclei: Tackling the Strong Interaction and Hunting for New Physics

Nuclei and hadrons are “laboratories” for exploring nature’s fundamental interactions. In this talk, I discuss the theoretical challenges and advances in the interpretation of experimental tests of fundamental symmetries performed with these strongly interacting systems. This theoretical work has enabled us to exploit such tests to achieve a deeper understanding of the dynamics of Quantum Chromodynamics in the non-perturbative regime and to gain a powerful new tool in the hunt for possible physics beyond the Standard Model.

Host: Pavel Fileviez

Continue reading… Michael J. Ramsey-Musolf (U. Mass Amherst/T. D. Lee Institute/Shanghai Jiao Tong U)

Continue reading… No seminar (total solar eclipse)

Thinking about sinking: the settling of shaped solids

The gravitational settling of particles in a viscous fluid is a common process in nature and
in industrial contexts. This familiar process is a confounding problem in many-body
physics due to the long-range, directional interactions between sinking particles. After
discussing some known facts and known puzzles in the field, I will present results that
show qualitatively new behaviour when the particles have non-trivial shape and
orientational degrees of freedom, as do snowflakes, plankton, crystals, and other natural
sediment. As examples of the richness that emerges from shape,

Continue reading… Narayanan Menon (U Massachusetts, Amherst)

Astrophysical Tau Neutrinos

Neutrinos are very reticent fundamental particles. Tau neutrinos make electron and muon neutrinos look
positively gregarious.  The IceCube Neutrino Observatory at the South Pole has sensitivity to all three active neutrino
flavors over an energy scale spanning six orders of magnitude.  We report on the first high-significance measurement of
the most energetic tau neutrino candidates ever observed.

Host: Benjamin Monreal

Continue reading… Doug Cowen (Penn State)

Exploring the Renormalization of the Galaxy Bias Expansion

The galaxy bias expansion links the galaxy overdensity field to the matter overdensity field δρ. In my talk, I will review the theoretical machinery that allows us to connect the primordial curvature fluctuations to the large-scale structures of the Universe, and I will present the results of 2306.08025. In this work, we performed the one-loop renormalization of the composite operator δρ², up to third order in gravitational evolution and in the presence of local non-gaussianities, using three distinct regularization schemes. I’ll show how this choice impacts the values of the counterterms,

Continue reading… Samuel Patrone (Caltech) 

A Spartan’s Quantum Journey
 
Samuel Schwab
 
Booz Allen Hamilton
 
Abstract:  This three part talk covers the nonlinear journey of a CWRU grad student to a career in quantum information science. This first part is a historical narrative of the journey while the remaining two are technical overviews of some of the most recent work in building and characterizing the necessary infrastructure for scaling up superconducting quantum systems and building a heterogeneous quantum network. Specifically these will be focused on using integrated photonic photodiodes as cryogenic microwave sources, and our efforts in testing acousto-optic transducers. 

Continue reading… Samuel Schwab (Booz Allen Hamilton)

Skyrmions and Topological Hall Effects in Chiral Magnets

Jiadong Zang

Department of Physics and Astronomy, University of New Hampshire

Abstract:  Chiral magnets are a series of magnets with broken inversion symmetry. A new type of spin interaction therein, the Dzyaloshinskii-Moriya interaction, stimulates the formation of many novel topological spin textures. One important example is the emergence of magnetic skyrmion, whose nontrivial topology enables unique dynamical property and thermal stability and gives rise to promising applications in future
spintronic devices. Other than neutron scattering and transmission electron microscopy, the topological Hall is an important identification of skyrmions.

Continue reading… Jiadong Zang (U of New Hampshire)

Optimizing Continental Scale Renewable Energy Systems

Widespread use of renewable electricity sources is necessary to address climate change, but
their intermittency, geospatial variability, and large land footprints create unique challenges for
optimizing deployment while respecting power flow and engineering constraints. In this talk, I
will review approaches to plan continental scale systems that are renewables dominant. I will
describe the key computational trade-offs and optimization methods that are used to plan land
use. Cost-effective deployment of high-penetration renewable energy systems depends not
only on technological and economic considerations but also on market institutions and policy
coordination.

Continue reading… Michael Davidson (University of California, San Diego)

Ultra high energy neutrino detection in Antarctic ice: an evolving story 

High energy astrophysics is now being probed using four different energetic messengers: (charged) cosmic rays, gamma rays, gravitational waves, and neutrinos.  The past decade and a half has been marked by discoveries of gravitational waves and neutrinos up to O(10^16 eV).   Neutrinos in the ultra-high energy (UHE) regime (above 10^18 eV) are an important missing piece of the multi-messenger picture of the high energy universe, and will also be important probes of new physics.  Experiments using radio techniques in Antarctic ice are the most promising for the discovery of UHE neutrinos.  

Continue reading… Amy Connolly (OSU)

Next Generation Power Electronics: From Wide Bandgap GaN to Ultrawide Bandgap Ga2O3, (AlxGa1-x)2O3 and LiGa5O8

Dr. Hongping Zhao, Professor

Department of Electrical and Computer Engineering, Department of Materials Science and Engineering, The Ohio State University 

Join Zoom (ID: 97121487193; psw: 731035)

Abstract: Wide bandgap gallium nitride (GaN) with intrinsic breakdown field of 3.5 MV/cm and a high electron mobility (phonon limited mobility >2000 cm2/Vs), possesses Baliga figure-of-merit at least 5 times superior to SiC and nearly 1000 times better than Si, enabling substantial reduction in conduction and switching losses in power electronics.

Continue reading… Hongping Zhao (OSU)

Continue reading… No colloquium – Spring Break

Continue reading… No seminar (Spring Break)

Continue reading… No colloquium – APS March Meeting

Continue reading… No seminar (APS March Meeting)

(Cancelled)

Continue reading… Florian Kuhnel

Fractals, multifractals, and conformal invariance at Anderson transitions

Ilya Gruzberg, Department of Physics, Ohio State University 

Zoom recording

Abstract: Anderson transitions (ATs) between metals and insulators or between topologically distinct insulators, share common features with conventional second-order phase transitions, such as the critical point of the Ising model for a magnet. However, ATs also exhibit many unusual features including the multifractal scaling of the critical wave functions. Conventional critical points possess conformal invariance which constrain their properties to the extent that they can be obtained exactly in two dimensions and to very high precision in three dimensions.

Continue reading… Ilya Gruzberg (OSU)

The price of evolution: how thermodynamics shapes gene regulation

Many of the physical processes in a cell consume energy, but we are only beginning to understand how these costs have influenced the course of evolution. Biology is strewn with counter-intuitively complex mechanisms whose evolutionary predecessors must have consumed significant energy resources without any clear fitness benefit.  So how do such mechanisms evolve in the first place, and how strong is the guiding hand of thermodynamic optimization?  My talk explores these issues through one specific example:  gene regulation in higher organisms (including humans) by microRNAs. These small RNA molecules (only 22 nucleotides long) are versatile tools for controlling the expression of genes into proteins,

Continue reading… Michael Hinczewski (CWRU Physics)

Mechanical sensors for dark matter and neutrinos

The development of optomechanical systems has revolutionized the detection of tiny forces over the past few decades. As such technologies reach (and surpass) quantum measurement limits, they can enable new searches for weakly coupled phenomena, including dark matter, gravitational waves, “fifth’’ forces, and sterile neutrinos. As a demonstration of these techniques, I will describe an initial search for dark matter using an optically levitated nanogram mass sensor, which can exceed the sensitivity of even large underground detectors for certain classes of dark matter candidates in a few days of exposure.

Continue reading… David Moore (Yale)

Theory for multiplets in solid state:  case studies in colors for transition metal oxides and bond disproportionation in rare-earth nickelates
 
Swagata Acharya
 
Scientist III, National Renewable Energy Laboratory, Golden, Colorado
 
Zoom Recording

Abstract: Colors in several transition metal oxides have often been ascribed to presence of defects/vacancies over the decades.
I will discuss results from our recent work that uses parameter free many body perturbative and exact local approaches
to describe the excitonic absorptions and their spin components that determine the color for these materials and that defects/vacancies were wrongly held responsible for the same.

Continue reading… Swagata Acharya (National Renewable Energy Lab)

Multi-field Wave Dark Matter
 
In this talk I will highlight some general aspects of an extension to the classic Ultra Light Dark Matter (ULDM) paradigm with a second light scalar particle. As experimental data is beginning to put more stringent constraints on single field ULDM, it is an interesting to explore what happens when more light particles are added to the picture. Having more light degrees of freedom present in our Universe might even be easier to reconcile with many UV completions of the Standard Model, where many scalars seem to be the norm and not the exception. 

Continue reading… Fabio van Dissel, IFAE (Barcelona)

Clinical metabolic magnetic resonance imaging

Kofi Deh,  Medical Physics at Howard University

Zoom recording

Talk Abstract: Spin hyperpolarization can increase the signal-to-noise ratio in magnetic resonance imaging (MRI) by a factor of 10,000, making it possible to perform metabolic imaging for early cancer detection. In this talk, we will look at the motivation for metabolic imaging, the physics of hyperpolarization and the technical considerations required for MRI of hyperpolarized X-nuclei. We will also look at practical considerations for translating this technology into the clinic. Finally, we will briefly examine other candidates for MR metabolic imaging that have less complexity than hyperpolarized MRI.

Continue reading… Kofi Deh (Howard University)

Dissecting Galaxies in the Distant Universe with JWST and Gravitational Lensing

The launch of JWST in December 2021 opened a powerful new eye onto the distant universe. The telescope’s high spatial resolution, large collecting area, and infrared wavelength coverage have enabled detailed studies of distant galaxies that were untenable with other instruments. Combining this powerful tool with strong gravitational lensing has been particularly exciting. Gravitational lensing magnifies distant galaxies, enabling detection of intrinsically smaller, fainter features than is possible in blank fields. In this talk, I will review some recent lensed galaxy results from JWST, and discuss how these new observations are shaping our understanding of the physics that govern galaxy evolution on small scales.

Continue reading… Brian Welch (NASA / University of Maryland)

Neutron Star Mergers: From gravity to nuclear and plasma astrophysics

Announcing the dawn of a new era of multi-messenger astrophysics, the gravitational wave event GW170817 – involving the collision of two neutron stars – was detected in 2017. In addition to the gravitational wave signal, it was accompanied by electromagnetic counterparts providing new windows into the different physics probed by the system. Since then, several gravitational wave events involving neutron stars have been discovered, with more expected over the next years. 

In order to understand and interpret the physics of these events, it is necessary to model the intricate dynamics of such systems before,

Continue reading… Elias Most (Caltech)

Power in Numbers: Cells, Collective Motion, and Coordinated Force 

Cells are energy transducers, using energy sources from their surroundings to create fascinating materials, which are capable of self-organizing, collectively moving, and remodeling their environment. My group explores how physical features of the cell’s environment impacts cell movement in both the context of bacterial biofilms and mammalian cells that move through changes in the cytoskeletal network. In this talk, I will present work on how collective groups of cells move and remodel their environment and how we can measure those collective forces even in complex environments, such as the extracellular matrix of mammalian tissues. 

Continue reading… Alison Patteson (Syracuse University)

Neutrino Physics and Dark Matter Searches at the Forward Physics Facility at the LHC

The recent observation of collider neutrinos by the FASER collaboration highlights the potential the forward direction at the LHC has for neutrino physics. In the HL-LHC era, we expect a significant number of neutrinos in the forward direction, opening the way for precision studies using collider neutrinos at the proposed Forward Physics Facility (FPF). In this talk, I will present some phenomenological studies in this direction. i) The electromagnetic properties of neutrinos (magnetic moments, milli-charge, charge radius) have attracted significant interest recently.

Continue reading… Roshan Abraham (UC Irvine)

Ken Singer (Physics) on the prize in Physics;

Clemens Burda (Chemistry) on the prize in Chemistry;

Michael Lederman (School of Medicine) on the prize in Physiology or Medicine;

David Clingingsmith (Weatherhead School of Management) on the Economics prize.

Continue reading… The 2023 Nobel Prizes

Near-Zero Field Magnetic Resonance Analysis of SiC devices at NASA’s Quantum Sensing and Spin Physics (Q-SASP) lab

Daniel R. Hart

NASA Glenn Research Ctr. (United States)

Zoom recording

Abstract:

Component analysis of devices and technologies that will be integrated to produce space instruments is needed for future NASA missions. For quantum communications, there is a need for quantum memory, quantum repeaters, single photon emitter, and detectors. For quantum sensing, extremely low Size, Weight, and Power (SWaP) and self-calibrating electrometers, magnetometers, and thermometers are needed with nano-scale resolution.

Continue reading… Daniel Hart (NASA Glenn)

 
Future of commercial human exploration – extreme environments (space and underwater habitats) 

This talk will provide a brief introduction to commercial human exploration in extreme environments for both space and underwater habitats. It will also cover tips and a case study in reviewing commercial companies to collaborate with and aid students in matching internships, co-ops, and employment. 

Adele Luta is an Exploration Extravehicular Activity Integration Manager and Human Systems Business Development Manager at Oceaneering International Inc. within the Space Systems Division.  

Continue reading… Adele Luta (Oceaneering International Inc)

Engineering tailored magnon modes for hybrid magnonics

Wei Zhang, Physics and Astronomy, UNC Chapel Hill

Abstract: Despite being a later entrant, the collective spin excitations (magnons) have recently received
increased attention in novel construction of hybrid systems exhibiting coherent phenomena. To
date, investigation of hybrid magnonic effects has been largely centered on the ferromagnetic
resonance and long wavelength modes. It remains challenging to incorporate short-wavelength
(deep mesoscale) modes for magnon hybridization, in which many fundamental questions, such
as the wavenumber-dependent coherent phenomena, remain unanswered. However, by exploiting
magnon-magnon coupled systems,

Continue reading… Wei Zhang (Univ. North Carolina at Chapel Hill)

Sunyaev-Zeldovich Science with Current and Future CMB Surveys.
 
Secondary anisotropies of the cosmic microwave background (CMB) are known to be remarkable probes of astrophysics and cosmology. The properties of free streaming CMB photons from the surface of last scattering are altered by their interaction with matter in the Universe carrying crucial information about the the epoch of reionisation and also the origin, growth, and evolution of structures. In this talk, I will discuss the potential of a couple of these secondary anisotropies, namely the kinematic and thermal Sunyaev-Zeldovich (SZ) effects, to shed light into some of the long-standing cosmological quests like the physics of reionisation and the properties of dark energy.

Continue reading… Srini Raghunathan (UIUC)

Near-Zero Field Magnetic Resonance Analysis of SiC devices at NASA’s Quantum Sensing and Spin Physics (Q-SASP) lab

Daniel R. Hart

NASA Glenn Research Ctr. (United States)

Abstract:

Component analysis of devices and technologies that will be integrated to produce space instruments is needed for future NASA missions. For quantum communications, there is a need for quantum memory, quantum repeaters, single photon emitter, and detectors. For quantum sensing, extremely low Size, Weight, and Power (SWaP) and self-calibrating electrometers, magnetometers, and thermometers are needed with nano-scale resolution. NASA Glenn’s Q-SASP is developing quantum metrology capabilities in silicon carbide (SiC) to evaluate the energy structure,

Continue reading… POSTPONED – Daniel Hart (NASA Glenn)

Nanophotonics to Efficiently Control Light-Matter Interactions at the Nanoscale

Christos Argyropoulos

Department of Electrical Engineering at Pennsylvania State University

Zoom recording

The field of nanophotonics has significantly evolved and matured during the last years mainly due to the rapid improvement in nanotechnology fabrication capabilities. In addition, currently we are able to accurately model and analyze very complex nanophotonic systems with dimensions ranging from nano to angstrom scales. Nanophotonics promise to efficiently control light at the nanoscale leading to the practical exploration of various emerging optical effects. In my talk,

Continue reading… Christos Argyropoulos (Penn State)

Putting the bang into the big bang

Inflation is the leading paradigm for the very early universe. Despite progress in inflationary model-building and CMB observations, the end of inflation and the exact mechanism through which energy is transferred from the inflationary to the SM and Dark Matter sectors remains largely uncharted. This era is called reheating and is necessary to provide the thermal radiation-dominated universe required for Big Bang Nucleosynthesis. Depending on the underlying particle physics model, reheating can lead to the population of hidden sectors and the creation of remnant particles or topological defects. It can thus be used to constrain theories of high-energy physics,

Continue reading… Evangelos Sfakianakis (CWRU)

Hybrid Neutrino Detection and Spectral Photon Sorting with Dichroicons
 

 
Hybrid Cherenkov/scintillation neutrino detectors represent the next generation of the remarkably successful photon-based neutrino detection program. These detectors have a broad physics program, from long-baseline neutrino oscillations, to solar and supernova neutrinos, and even neutrinoless double beta decay with sensitivities beyond the next-generation “tonne-scale.” There are many ways to discriminate between “chertons” and “scintons” in a big detector, including fast timing, slow scintillators, or by reducing the fraction of scintillation light.  I will discuss the development of a new approach, which sorts photons by wavelength,

Continue reading… Josh Klein (U Penn)

TBA. 

Host: Pino Strangi

Continue reading… POSTPONED – Mohamed ElKabbash (U Arizona)

Controlling stochastic biophysical processes, from protein folding to evolution

The chemical reaction networks that regulate living systems are all stochastic to varying degrees.  The resulting randomness affects biological outcomes at multiple scales, from the probability that a single protein molecule successfully finds its folded state to the evolutionary trajectory of a population of cells.  Understanding how the distribution of these outcomes changes over time is often difficult, and achieving control over this distribution via external interventions is an even more complex challenge.  Intriguingly, this problem has close parallels in a very different domain:  manipulating quantum states for applications like quantum computing and cold atom transport. 

Continue reading… Michael Hinczewski (CWRU)

Simulating Stochastic Gravitational Waves from Early Structure Formation

Gravitational wave detectors provide a chance to observe the state of the very early universe and have important sensitivities for studies of early universe cosmology and searches for physics beyond the Standard Model. In this talk, I will discuss the production of potentially detectable stochastic gravitational wave backgrounds in early matter dominated eras in the linear and nonlinear regimes of structure formation.

Continue reading… Joshua W Foster (MIT)

Atomic Layer Nanoelectromechanical Systems (NEMS)
for Classical and Quantum Signal Transduction

Philip Feng
Department of Electrical & Computer Engineering, University of Florida

(Respecting the speaker’s preference, the seminar was not recorded)

Abstract: Emerging atomically thin semiconductors (such as transition metal dichalcogenides (TMDCs), phosphorene, silicene), along with their heterostructures (particularly with graphene and hexagonal boron nitride (h-BN) layers), offer compelling platforms for creating new resonant nanoelectromechanical systems (NEMS) for multiphysics transducers, where the unconventional properties of these crystals can be harnessed for engineering both classical and quantum signal processing and sensing schemes. 

Continue reading… Philip Feng (University of Florida)

Via Zoom 

Link to zoom meeting

Discoveries in the Kuiper Belt, and how satellites will make future discoveries harder

The Outer Solar System Origins Survey (OSSOS) and affiliated surveys have now discovered over 1,300 new Kuiper Belt Objects (KBOs) with precisely measured orbits and known observation biases.  I will discuss what those discoveries mean for the “clustered” KBOs that led to the Planet 9 theory, and discuss a new, deeper survey currently in progress on the Canada-France-Hawaii Telescope that will discover some of the smallest and most distant KBOs.

Continue reading… Samantha Lawler (University of Regina)

Massless and Partially Massless Limits in Quadratic Gravity 
 
In the context of perturbative quantum field theory, the addition of quadratic-curvature invariants to the Einstein-Hilbert action makes it possible to achieve strict renormalizability in four dimensions. The additional quadratic terms are multiplied by dimensionless coefficients that are related to the masses of the extra gravitational degrees of freedom and to the interaction couplings. The aim of this talk is to analyse the limit of the theory in which the Weyl-squared coefficient tends to infinity. Remarkably, the result of this limit turns out to be sensitive to the presence of a cosmological constant:  when the latter is zero we have a massless limit for the spin-2 ghost,

Continue reading… Luca Buoninfante (Nordita in Sweden)

Orbital Angular Momentum of Magnons

Randy S. Fishman

Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

Abstract: The past 13 years have seen remarkable advances in the field of  “magnonics”, which focuses on the quanta of spin excitations known as magnons.  One of the main goals of magnonics is the storage and processing of information.  In quick succession, experimentalists discovered that magnons can produce the thermal Hall and Seebeck effects.   Almost all previous theoretical work in magnonics has been based on the Berry curvature,

Continue reading… Randy Fishman (Oak Ridge)

The Art and Science of Molecular Beam Epitaxy

—From Quantum Anomalous Hall Effect to Interfacial Superconductivity

Cui-Zu Chang

Department of Physics, Pennsylvania State University

(Respecting the speaker’s preference, the seminar was not recorded)

In this talk, I will briefly introduce the molecular beam epitaxy (MBE) growth mechanism and then focus on my research, which centers on the MBE growth of quantum materials, spanning from topological materials to interfacial superconductors. I will talk about two solid-state phenomena with zero resistance: the quantum anomalous Hall (QAH) effect and the interface superconductivity.

Continue reading… Cui-Zu Chang (Penn State)

Dark Energy & Gravitational Condensate Stars, Or What’s the (Quantum) Matter with Black Holes?

The difficulties in reconciling Einstein’s classical General Relativity and quantum theory reach their apex in the twin puzzles of black holes and cosmological dark energy. Both of these problems are evidence that the gravitational sector of the Standard Model is incomplete at macroscopic distance scales. Indeed when General Relativity is treated as a low energy Effective Field Theory, it can be shown that it necessarily receives infrared relevant corrections from the fluctuations of massless or light quantum fields. The associated conformal anomaly implies the existence of a new massless scalar degree of freedom in gravity,

Continue reading… Emil Mottola (Univ of New Mexico)

Mapping Dark Matter in the Milky Way using Normalizing Flows and Gaia DR3

 
We present a novel, data-driven analysis of Galactic dynamics, using unsupervised machine learning — in the form of density estimation with normalizing flows — to learn the underlying phase space distribution of 6 million nearby stars from the Gaia DR3 catalog. Solving the collisionless Boltzmann equation with the assumption of approximate equilibrium, we calculate — for the first time ever — a model-free, unbinned, fully 3D map of the local acceleration and mass density fields within a 3 kpc sphere around the Sun.

Continue reading… Sung Hak Lim (Rutgers)

Coherent light-matter interaction in van der Waals materials
 
Hui Deng
 
Department of Physics, University of Michigan
 
Zoom recording
 
Abstract: Many van der Waals semiconductors feature large oscillator strengths and, at the same time, the flexibility to construct heterostructure and to integrate with a variety of substrates. Therefore they allow studies of coherent light-matter interactions that have been difficult to access in traditional materials. We will discuss a few different types of 2D material systems where coherent light-matter interactions lead to quasi-particles of novel properties and may enable control of the properties of matter systems.

Continue reading… Hui Deng (U Michigan)

Cosmological Claims That Cause Michelson & Morley Conniptions
 
Researchers using data from the Planck satellite, a spacecraft measuring the cosmic microwave background (CMB), say they’ve observed a hint (at >99.2 percent confidence) of parity violation on cosmic scales. If confirmed, this result would have profound implications, not just for cosmology, but for all of fundamental physics, including Lorentz Invariance. In this seminar, I will review the basis for the claimed hint of so-called Chern-Simons’ cosmic birefringence. I will outline steps scientists are taking to definitively confirm (or falsify) this provocative claim using CMB experiments like the Simons Array,

Continue reading… Brian Keating (UCSD)

Fall 2023 Gundzik Colloquium
 
Revealing the history and future of the universe with the Cosmic Microwave Background
 

Measurements of the cosmic microwave background (CMB) serve as a potent tool for understanding the genesis, composition, and development of our Universe. The rate at which we are capable of mapping the CMB is outpacing Moore’s law, increasing by about an order of magnitude every five years. This rapid development has led to remarkable scientific discoveries such as confirming the geometry of our universe, refining theories of its primordial state, and solidifying our grasp on the Lambda-CDM model.

Continue reading… Brian Keating (UCSD)

Resurgence in III-Nitride Semiconductor Science and Applications via New Extreme Bandgap Semiconductor Discoveries

W. Alan Doolittle

School of Electrical and Computer Engineering, Georgia Institute of Technology

Zoom recording

Abstract: After revolutionizing lighting technology in the 1990/2000’s and high-power RF technologies in 2000/2010’s III-Nitride semiconductors seemingly took a hiatus as commercial markets matured and research waned. But recently two exciting discoveries have reenergized the III-Nitride community, offering pathways to optical devices with unprecedented photon energies and high voltage, power and temperature electronics.

Recently,

Continue reading… William Alan Doolittle (Georgia Tech.)

Detection of 21cm emission from Large Scale Structure with CHIME

Current cosmological measurements have left us with deep questions about our Universe: What caused the expansion of the Universe at the earliest times? How did structure form? What is Dark Energy and does it evolve with time? New experiments like CHIME are poised to address these questions through 3-dimensional maps of structure using the 21cm emission line from neutral hydrogen contained in abundance in galaxies. In this talk, I will describe recent results from the CHIME experiment that show a significant detection of neutral hydrogen in distant galaxies and future directions for the analysis.

Continue reading… Laura Newburgh (Yale)

PLEASE NOTE SPECIAL TIME/LOCATION

“Quantum Biology”: how nature harnesses quantum processes to function optimally, and how might we control such quantum processes to therapeutic and tech advantage

Imagine driving cell activities to treat injuries and disease simply by using tailored magnetic fields. Many relevant physiological processes, such as: the regulation of oxidative stress, proliferation, and respiration rates in cells; wound healing; ion channel functioning; and DNA repair were all demonstrated to be controlled by weak magnetic fields (with a strength on the order of that produced by your cell phone).

Continue reading… Clarice D. Aiello (UCLA, Quantum Biology Tech (QuBiT) Lab)

Probing the Structure and Evolution of Our Universe with Line Intensity Mapping with mm-Wavelength Instruments

I will discuss line intensity mapping (LIM) and its applications for understanding cosmology and star-formation across cosmic time. I will focus on TIME, a mm-wavelength instrument designed to use LIM to probe the [CII] line at redshifts ~5-9 and the CO lines at redshifts ~0.5-2. The instrument is a grating spectrometer with transition edge sensors that is used on the Arizona Radio Observatory 12m. I will also briefly touch on other instruments and facilities (including the Fred Young Submillimeter Telescope) that will be used for LIM and the future of cosmology using this technique. 

Continue reading… Abby Crites (Cornell)

The eXciton Franz Keldysh effect: Spectrally measuring electric fields using the electron-hole interaction in wide band gap materials

Roberto C. Myers

Professor of Materials Science, Electrical Engineering, and Physics, The Ohio State University

Zoom recording

Abstract: Wide band gap materials can sustain large electric fields up to a point. When the field is large enough,  electrons and holes and tunnel between the typically well separated conduction and valence band states causing an avalanche of current, which destroys the device. This dielectric breakdown occurs at local positions in devices where the field lines are concentrated.

Continue reading… Roberto Myers (Ohio State University)

New Challenges in Fire Safety: From Earth to Space

The controlled use of fire dates back 400,000 years. Fire has played a crucial role in human history, allowing safe consumption of meat, expanding the range of inhabitable land (to colder regions), and providing an energy source. Fire also poses a great threat to life and property (e.g., forest fires). However, the science of fire has not been explored until the past few decades, and our understanding of fire dynamics is far from complete. Furthermore, ever-evolving technologies present new challenges for fire safety every day. In this talk,

Continue reading… Ya-Ting Liao (CWRU Mechanical and Aerospace Engineering)

A cautionary case of casual causality – Diagnosing (a)causality in the EFT of gravity

In recent years, causality has emerged as a powerful criterion to distinguish between effective field theories (EFTs) arising from physical and unphysical high-energy theories.

A direct way to ensure a given EFT is causal is to demand a lower bound on scattering time delays, which essentially imposes a speed limit averaged over the trajectory. In flat space, this is unambiguously dictated by the Minkowski light cones, but the situation is more subtle with dynamical gravity. I will make the case that the relevant notion is so-called infrared (IR) causality.

Continue reading… Calvin Y Chen (Imperial College London)

Effects of disorder and hydrogenation in intrinsic magnetic topological insulators

Kyungwha Park

Department of Physics, Virginia Tech

Abstract:
Topological insulators have gapless Dirac surface states that are protected by a topological invariant in the presence of time reveral symmetry. When time reversal symmetry is broken, the Dirac surface states are gapped and interesting features are expected such as quantum anomalous Hall (QAH) effect, topological magnetoelectric effect, and axion physics. In particular, when ferromagnetic order is formed within topological insulators (i.e., magnetic topological insulators) in zero magnetic field, the QAH effect can be realized for the chemical potential tuned within the surface gap such that the Hall conductance is quantized and chiral charge currents flow around the edges without dissipation.

Continue reading… Kyungwha Park (Virginia Tech)

MPPL Physics Colloquium – Neutrino windows to new physics

Neutrinos are the most elusive particles of the Standard Model even though they are extraordinarily abundant in the Universe. In our quest to uncover all mysteries of the neutrino sector we encountered one of the most surprising characteristics of neutrinos: Neutrinos oscillate, i.e. they can change their flavor when traveling over a distance. This implies that neutrinos are massive, in contradiction with the Standard Model of particle physics, therefore making neutrinos a potential window to a new sector of particle physics.

In the colloquium I will elaborate on how neutrinos can shine light on physics beyond the Standard Model.

Continue reading… Julia Gehrlein (CERN – MPPL 2023 Winner)

Neutrino windows to new physics

Neutrinos are the most elusive particles of the Standard Model even though they are extraordinarily abundant in the Universe. In our quest to uncover all mysteries of the neutrino sector we encountered one of the most surprising characteristics of neutrinos: Neutrinos oscillate, i.e. they can change their flavor when traveling over a distance. This implies that neutrinos are massive, in contradiction with the Standard Model of particle physics, therefore making neutrinos a potential window to a new sector of particle physics. In the colloquium I will elaborate on how neutrinos can shine light on physics beyond the Standard Model.

Continue reading… Julia Gehrlein (CERN) Michelson Postdoctoral Prize Colloquium

MPPL Lecture 2 – Who ordered that? Probing neutrino flavor models with precision neutrino experiments

The observed flavor pattern of neutrinos, their large mixings and the smallness of their masses compared to the masses of the other fermions provides a great puzzle. In this talk I will review explanations to this puzzle based on symmetries and then focus on the predictions and testability of these flavor models. I will put a particular focus on the most predictive class of models which relate different observables with each other.

I will show how upcoming neutrino experiments like oscillation experiments,

Continue reading… Julia Gehrlein (CERN – MPPL 2023 Winner)

MPPL Lecture 1 – To break CP or to not break CP – Hints for new CP violating physics in long baseline neutrino oscillations

The quest for leptonic CP violation is one of the major goals of near future neutrino oscillation experiments like DUNE and Hyper-Kamiokande. Experiments of the current generation like NOvA in the US and T2K in Japan do not have enough sensitivity to claim a significant discovery of CP violation however they provide already hints for the value of the CP violating quantity. Interestingly, their results currently mildly disagree with each other.

Continue reading… Julia Gehrlein (CERN – MPPL 2023 Winner)

Heavy States in 3d Gravity and 2d CFT
 

One way to learn about black holes and other heavy states in quantum gravity is to study their response to perturbations by light probe fields. In 3d gravity and holographic 2d CFTs, it is often possible to do this exactly. We consider the propagator of free scalar fields in AdS geometries with a conical defect or a BTZ black hole, dual on the boundary to a heavy-light 4-point function. In the bulk, the correlator can be computed by solving the equation of motion, as well as by the method of images. 

Continue reading… David Grabovsky (UC Santa Barbara)

Continue reading… No seminar (faculty meeting)

Gravitational waves with astrometry in the Gaia era
 

Gravitational waves have a periodic effect on the apparent positions of stars on the sky. This effect can be quantified and ultra-precise astrometric measurements (like the ones from Gaia) can be used as a new method to search for gravitational signals. I will describe the principles which give rise to the astrometric signature of gravitational waves, and examine this result in the context of Einsteinian and alternative polarization states. I will discuss some of the data analysis challenges that will have to be overcome when trying to search for GWs in the extremely large (>10^9 stars) Gaia data set,

Continue reading… Deyan Mihaylov (CWRU)

Continue reading… No seminar (Labor Day)

Synthesis and Characterization of γ-Graphyne, a Novel Allotrope of Carbon

Valentin O. Rodionov

Department of Macromolecular Science and Engineering, Case Western Reserve University

Abstract: The unique ability of carbon to bond with itself forming extended chains and networks underlies the structural complexity of organic matter. This complexity extends to elemental carbon. Several hundred crystalline carbon phases have been theoretically predicted to date. However, few of these materials have been realized experimentally. Advances in the synthesis of nonbenzenoid and sp1-containing allotropes have been especially limited. One of such allotropes is γ-graphyne,

Continue reading… Valentin O. Rodionov (CWRU)

TBA. 

Host: Xuan Gao

Continue reading… POSTPONED – Philip Feng (U Florida)

 New Ideas for hunting light dark matter
 
Abstract: The nature of dark matter remains one of the great puzzles in physics. Although current direct detection experiments based on nuclear recoil have reached outstanding sensitivities, light dark matter models with particle mass below the GeV scale are still largely unconstrained. I will present new ideas for seeking light dark matter candidates by exploiting synergies with developing technologies in tabletop experiments. Particularly, I will examine a proposal to use atom interferometers to detect a light dark matter subcomponent at sub-GeV masses through quantum decoherence, and will present a novel technique for detecting axions or axion-like particles with optomechanical cavities. 

Continue reading… Clara Murgui (Caltech)

New Dimensions on the Interaction of Light and Matter: Quantum Materials, Quantum Light, and Quantum Control

The quantum conception of light consisting of particles of discrete energy, or photons, underlies its interaction with matter. For solid materials, this understanding has led to transformational applications both as conventional as sensor and display technologies and as extraordinary as lasers. Despite this ubiquity, advances in materials continue to reveal nuances in the interaction of light with matter. The emergence of layered materials of atomic-scale thickness presents a new two-dimensional (2D) landscape in which to play with the interaction between photons and matter,

Continue reading… Nate Stern (Northwestern University)

What is the simplicity of the early universe trying to tell us?

 
After reviewing some key hints and puzzles from the early
universe, I will introduce recent joint work with Neil Turok
suggesting a rigid and predictive new approach to addressing them.

Our universe seems to be dominated by radiation at early times, and
positive vacuum energy at late times.  Taking the symmetry and
analyticity properties of such a spacetime seriously leads to a new
formula for the gravitational entropy of our universe, and a picture
in which the Big Bang may be regarded as a kind of mirror.

Continue reading… Latham Boyle (Perimeter)

Topological spin textures and Hall effects in chiral magnets

Mohit Randeria

Physics Department, The Ohio State University

Abstract: Skyrmions are topological solitons that were first discussed in quantum field theory in the 1960’s. In recent years, through a series of beautiful experimental developments, they have become of great relevance to condensed matter systems, especially in chiral magnetic materials.

I will begin my seminar with a pedagogical introduction to skyrmions and explain how these spin textures arise naturally in magnets with broken inversion symmetry and spin-orbit coupling. I will describe a variety of experiments emphasizing the unusual properties of skyrmions and their potential applications.

Continue reading… Mohit Randeria (Ohio State University)

Bootstrapping Inflation
 
The large-scale correlations that we observe in the distribution of matter in the universe have their origins in primordial perturbations produced prior to the hot big bang—likely during a period of inflationary expansion. Interestingly we do not directly observe the inflationary epoch, but instead infer its dynamics from correlations residing on the late time boundary of the inflationary spacetime where the universe reheats. This motivates us to ask whether we can understand things directly on this asymptotic boundary, without making explicit reference to bulk time evolution. I will describe progress in this direction, including some aspects of how bulk time evolution is encoded in observable quantities.

Continue reading… Austin Joyce (Astronomy and Astrophysics, University of Chicago)

Gravity as a phase of matter

I will discuss how generalized symmetries and their anomalies can be used to constrain low-energy effective field theories (EFTs). In particular, I will present EFTs enjoying biform symmetries, which are a slight variation of higher-form symmetries, and are defined by the presence of a conserved current that has the symmetries of a Young tableau with two columns of equal length. When these theories also have a topological biform current, its conservation law is anomalous, and this is sufficient to fix the current-current correlation function and infer the presence of a massless mode in the spectrum. 

Continue reading… Greg Mathys (Cornell)

Title: Non-invasive and Quantitative Phase Microscopy

Abstract: Image contrast is critical to many fields, such as microbiology, which studies biological samples that can be as tiny and thin as a single cell. A significant problem in visualizing cells is that they are nearly transparent (phase objects), making them difficult to observe using conventional microscopes. Approaches to image biological objects require the samples to be stained and thereby converted to an amplitude object. However, staining has plenty of drawbacks: 1) it is invasive because staining chemicals may alter the structure of the object being studied;

Continue reading… Rosario Porras-Aguilar (UNC Charlotte)

Coupled Early Dark Energy
 
I will describe how some of the fine-tuning problems of the early dark energy solution to the Hubble tension can be addressed using couplings to other fields already present in cosmology. I will discuss the formulation, the cosmology, and the constraints on such models, arising from both observational and theoretical considerations. I will also address some very recent claims about the viability of such approaches.

ZOOM ID: 999 3023 4812, Passcode: PAsems

https://cwru.zoom.us/j/99930234812?pwd=a0tid3VOTzJHTkxBWnNjWmtsNmd5UT09

Continue reading… Mark Trodden (U Penn)

Spin-orbit Torque and Magnetoresistance Phenomena in Layered Quantum Materials

Simranjeet Singh

Department of Physics, Carnegie Mellon University

Layered quantum materials, such as WTe2 and MoTe2, host plethora of novel phenomena that are highly relevant for quantum spintronics, namely: Dirac type dispersion, strong spin-orbit coupling (SOC), Fermi arcs, and helical spin-momentum locked surface and bulk states. These systems provide a distinct opportunity to obtain highly efficient and unconventional charge to spin conversion owing to strong SOC, symmetry breaking, and these topology-based phenomena. On the other hand, spin-orbit torque (SOT) driven deterministic control of the magnetic state of a ferromagnet with perpendicular magnetic anisotropy is key to next generation spintronic applications including non-volatile,

Continue reading… Simranjeet Singh (Carnegie Mellon)

Link to video 
 
Progress in nuclear fusion: hope or hype?
 
 On December 13, 2022, the Department of Energy announced “fusion ignition,” an “energy breakthrough” that received massive publicity.  It was “a long-awaited milestone in reproducing the power of the sun in a laboratory” as well as, according to White House Science Adviser Arati Prebhakar, a sign of possible progress “to the possibilities for clean energy.”Yet December’s milestone was “long-awaited” because physicists have been seeking ways to control and use fusion reactions at least since the 1950s, with extremely limited success. The big news was that researchers at Lawrence Livermore National Laboratory for the first time ever created a reaction that produced more energy than was used to start the reaction.

Continue reading… Cyrus Taylor and Philip Taylor (CWRU Physics)

Cancelled for this semester

Continue reading… Kersten Perez (Columbia)

Superconductivity at interfaces of KTaO3 and its possible origin.

Anand Bhattacharya

Materials Science Division, Argonne National Laboratory

Abstract:

Superconductivity in materials with broken inversion symmetry and strong spin-orbit coupling can lead to unconventional pairing states that may be of interest in quantum science and technology. In this seminar I will discuss a recently discovered superconducting electron gas formed at interfacesof a 5d transition metal oxide KTaO3 (KTO) that combines these attributes intrinsically, and whose unique properties provide strong clues about the origin of its superconductivity.

Continue reading… Anand Bhattacharya (Argonne National Lab)

Continue reading… No colloquium – Spring Break

Continue reading… No Colloquium – APS March Meeting

TeV-scale LNV: 0νββ-decay, energy frontier probes, and the origin of matter

Lepton number violation (LNV) is a very attractive research topic for theoretical and experimental physicists due to its implications beyond the Standard Model. It provides feasible theoretical explanations to several open questions in particle physics (e.g., the origin of neutrino mass) and has a rich phenomenology at different energy scales. We explore the underlying connections between neutrinoless double −decay (0) experiments, hadron colliders, and cosmology observations. In the context of simplified models, we show that future collider and 0 experimental results may complement each other.

Continue reading… Sebastian Urrutia-Quiroga (U. Mass)

Continue reading… No seminar (APS March Meeting)

The Conformal Bootstrap: An overview of recent analytical and numerical approaches. 
 
Abstract: 

Conformal field theories have been long known to describe the universal physics of scale invariant critical points, such those occurring at regions near to continuous phase transitions in fluids, ferromagnets and  quantum field theories. Studying conformal field theories would help us to understand those universal characteristics that relate several seemingly unrelated physical systems. Also from a renormalization group perspective, studying the space of conformal field theories amounts to studying the space of all well-defined (or UV complete) quantum field theories.

Continue reading… Carlos Cardona (CWRU)

Quantum Time Machines: Hunting Down Time Series Anomalies Like a Boss

Santosh Kumar 

Agnostiq, Ontario, Canada

Zoom recording

The task of identifying abnormal behavior in time series data is essential in many fields ranging from financial markets to biophysics. While traditional algorithms for time series anomaly detection (TAD) have proven to be effective, the advent of newly accessible quantum processing units (QPUs) presents an opportunity to explore a quantum approach to TAD. This talk will introduce a new TAD algorithm called Quantum Variational Rewinding (QVR)[1,2,3], where we map and learn time series processes by embedding classical data into quantum states and rewinding them to their learnt initial state –

Continue reading… Santosh Kumar (Agnostiq)

Measuring CMB Polarization from the Stratosphere

Measurements of the polarization of the Cosmic Microwave Background (CMB) are a powerful probe of the composition and evolution of the Universe.  Observing from the stratosphere with balloon-borne telescopes provides access to information at high frequencies and on the largest spatial scales.  In this talk, I will discuss what we can learn about cosmology from CMB polarization in the context of two experiments. SPIDER is a balloon-borne telescope designed to look for a signal from cosmic inflation over the course of two Antarctic flights.  The second of these flights, which concluded in January of this year,

Continue reading… Johanna Nagy (Washington University, St Louis)

Field-space surprises in multi-field preheating
 
I will discuss preheating in multi-field models of inflation with a curved field-space manifold, focusing on two well-studied families of models. 
The first includes Higgs inflation and models where the fields couple non-minimally to gravity. I will describe both analytical progress as well as recent lattice simulations that have been used to capture significant nonlinear effects like backreaction and rescattering. I will show how we can extract the effective equation of state and typical time-scales for the onset of thermalization, quantities that could affect the usual mapping between predictions for primordial perturbation spectra and measurements of anisotropies in the cosmic microwave background radiation.

Continue reading… Evangelos Sfakianakis (CWRU)

Manipulation of Quantum Materials Through Strain

Na Hyun Jo

Department of Physics, University of Michigan

A major question in basic physical research is how to understand the collective behavior of interacting quantum objects that cannot be treated as non-interacting particles. Many-body interactions in complex quantum materials are an ideal platform because the interactions cause fascinating phenomena such as high-temperature superconductivity, exotic magnetic systems, correlated topological materials, and many others. In addition, four fundamental degrees of freedom, lattice, charge, orbital, and spin, provide strong tunability on the exotic properties, which allow enhancing our understanding of interacting quantum objects.

Continue reading… Na Hyun Jo (U Michigan)

The Second Kind of Impossible

A dozen years ago, seven Russians, five Americans, an Italian and a black cat named Bucks began an expedition across the tundra of far eastern Russia north of the Kamchatka Peninsula on an unpromising search for what many believed to be impossible.  The talk will describe what they were looking for, what they actually found, and what has been learned in the years since.

Continue reading… Paul Steinhardt (Princeton)

Co-sponsored by the Departments of Chemistry and Physics and the Program in Cell Biology.

Jesse Berezovsky (Physics) on the prize in Physics; Metin Karayilan (Chemistry) on the prize in Chemistry; and Cynthia Beall (Anthropology) and Patricia Princehouse (Institute for the Science of Origins) on the prize in Physiology or Medicine. 

The Nobel Prize in Physics 2022 was awarded to Alain Aspect, John F. Clauser and Anton Zeilinger for experiments with entangled photons, elucidating the bizarre nature of quantum mechanics, and setting the stage to develop new types of quantum technology. Though quantum mechanics had already revolutionized science and technology by the mid-20th century,

Continue reading… The 2022 Nobel Prizes in Science

Dynamical Inflation Stimulated Cogenesis
 
We propose a minimal setup in order to realise dynamical inflection point inflation along while generating the baryon asymmetry of the universe via leptogenesis and dark matter simultaneously. A dark SU(2)D gauge sector with a dark scalar doublet playing the role of inflaton is considered along with several doublet and singlet fermions sufficient to realise multiple inflection points in the inflaton potential. While some of these doublet fermions play the role of dark matter, the rest of the fermions can play non-trivial role in generating light neutrino masses via seesaw mechanism while also leading to non-zero lepton asymmetry from out-of-equilibrium decay of heavy fermions.

Continue reading… Arnab Dasgupta (PITT PACC – Univ. of Pittsburgh)

Nanocomposite Soft Magnetic Materials Consideration of Domains and Domain Walls

Prof. Matthew A. Willard

Department of Materials Science and Engineering, Case Western Reserve University

Abstract: Magnetic alloys with nanocomposite microstructures possess some of the smallest coercivities ever measured.  The combination of phase selection and microstructure refinement are responsible for the remarkable easy in switching.  In such materials, the magnetic domain walls become exceedingly wide primarily due to a microstructure-induced reduction in magnetocrystalline anisotropy.  In this seminar, the increase in magnetic domain wall width and its estimated size considering the random anisotropy model will be presented. 

Continue reading… Matthew Willard (MSE, CWRU)

Nonreciprocal spin and charge transport in magnetic and topological materials system

Nonreciprocal transport of spin and charge carriers may take place in materials systems that lack inversion symmetry. One prominent example is the p-n junction — the building block of various semiconductor devices (such as transistors, solar cells, LEDs, etc.) that have been an indispensable part of our daily lives. Recently, there has been a surge of interest in nonreciprocal transport effects emerging in magnetic and topological materials systems. Fundamentally, these nonreciprocal-response effects touch upon several key elements of modern condensed-matter physics, such as symmetry, band topology,

Continue reading… Shulei Zhang (CWRU)

In Search of Cosmic-Ray Antinuclei from Dark Matter with the GAPS Experiment

The origin of dark matter is a driving question of modern physics. Finding dark
matter in the laboratory and elucidating its properties could revolutionize our
understanding of the fundamental building blocks of the universe. The common
challenges for dark matter searches in astrophysical signatures are large and
uncertain backgrounds. The General Antiparticle Spectrometer (GAPS) is a
balloon-borne experiment designed to identify low-energy cosmic antinuclei, in
particular antideuterons from dark matter annihilation or decay. With a novel
detection approach that uses the uniquely characterized atomic X-rays and
charged particles from the decay of exotic atoms,

Continue reading… Mengjiao Xiao (MIT)

Cosmological Phonon Collider 
 
Inflation can be viewed as a natural particle collider through which we can learn about physics at very short distances. In this talk, I study the physics of the cosmological phonon collider: I uncover the imprints of heavy particles during inflation on the correlators of the Goldstone boson of the broken time diffeomorphism during inflation. I show that the reduced speed of sound for the Goldstone allows new types of footprints of heavy fields to emerge. In particular, I will demonstrate that the exchange of supersonic, massive fields that are still lighter than Hubble divided by the speed of sound induces characteristic resonances in the soft limit of the bispectrum.

Continue reading… Sadra Jazayeri (Institut d’Astrophysique de Paris)

Chirality and Topology in DNA-type Chiral Materials

Binghai Yan

Department of condensed matter physics, Weizmann Institute of Science, Israel

Abstract: In physics, chirality usually refers to the locking of spin and momentum, such as in Weyl fermions and circularly-polarized light. In chemistry and biochemistry, however, it is the geometric asymmetry of non-superposable left or right-handed mirror images that constitutes chirality. While seemingly unrelated characters in different fields, the chiral geometry can lead to topological electronic properties in chiral molecules or solids, as we recently discovered in theory and experiments.

Continue reading… Binghai Yan (Weizmann Institute of Science, Israel)

DNA Nanotechnology Tools for Single-Molecule Cryo-EM of Membrane Proteins

DNA is a unique polymer. It is the information storage molecule of all known life forms, but can also be used to build up complex, artificial structures that are not found in Biology. Our group is leveraging this programmability to engineer nanoscale architectures and tools for applications in Biophysics and Structural Biology.

I will demonstrate how DNA-lipid nanodiscs1 can be made and used as novel molecular tools to study membrane proteins (MPs) in a native membrane-like environment. MPs are key players in cellular functions such as sensing,

Continue reading… Thorsten Schmidt (Kent State University)

High performance plasmonic and polaritonic materials platforms

Jonathan A. Fan

Associate Professor, Department of Electrical Engineering, Stanford University

Abstract: I will discuss new classes of nanophotonic materials that serve as ideal model systems for infrared optoelectronic devices.  First, I will introduce a new method for growing single crystal plasmonic metal structures on amorphous substrates based on the concept of rapid melt growth.  I will show how these concepts can extend to the reliable growth of bi-crystal gold microstructures and be used to elucidate the photothermoelectric properties of individual grain boundaries. 

Continue reading… Jonathan A. Fan (Stanford)

 
Fundamental Tests of Quantum Mechanics with the Majorana Demonstrator

 
The Majorana Demonstrator is an ultra-low-background experiment, with a primary physics goal to search for neutrinoless double beta decay of 76Ge.  The Demonstrator consisted of two modules of p-type point-contact (PPC) germanium detectors operating inside a large passive shield on the 4850’ level of the Sanford Underground Research Facility in Lead, SD.  The same design features and data that underpin the neutrinoless double beta decay search – low backgrounds, excellent energy resolution, and sharp pulse characteristics – also enabled a variety of searches for Beyond the Standard Model (BSM) physics.  

Continue reading… Walter Pettus (Indiana U)

POSTPONED!

TBA. 

Host: Kathleen Kash

Continue reading… ***POSTPONED***Alp Sehirlioglu (CWRU)

Advances in functional magnonic materials: spin waves in reconfigurable nanostructures and hybrid systems

Benjamin Jungfleisch

Department of Physics and Astronomy, University of Delaware, USA

Join Zoom 

Magnons, the quantum-mechanical excitations of spin waves, are bosons whose number does not need to be conserved in scattering events. The field of magnonics aims to manipulate the properties of these fundamental magnetic excitations for practical applications. Information transfer and processing based on magnons do not suffer from Joule heating. Hence, magnonics may lead to alternative information technologies with lower power consumption that meet the demands for a carbon-neutral future.

Continue reading… M. Benjamin Jungfleisch (University of Delaware)

Join Zoom Meeting

https://cwru.zoom.us/j/95387840890?pwd=WU4ydzhJRVJtekc4MlVLNStJdll0UT09

Meeting ID: 953 8784 0890

Passcode: 975081

Super-resolution imaging of complex materials: chromatography and (extra)cellular nutrients

Lydia Kisley, Warren E. Rupp Assistant Professor, Case Western Reserve University, Departments of Physics and Chemistry

Abstract: Single-molecule spectroscopy and super-resolution fluorescence microscopy have become seminal tools for scientists due to their ability to resolve heterogeneity normally obscured in traditional ensemble measurements. Single-molecule spectroscopy has enabled important findings in areas such as cellular biophysics and catalysis, yet, single-molecule techniques have had limited use in the study of materials.

Continue reading… Lydia Kisley (CWRU)

Title: Dynamic DNA Nanotechnology

Sebastian Sensale Rodriguez

Assistant Professor
Department of Physics
Cleveland State University

Abstract: Taking inspiration from macroscopic machines, the last decade has seen a surge of interest in the development of DNA origami devices whose functions heavily rely on conformational changes. These “dynamic” DNA nanodevices have found application in diverse areas of research including drug delivery, molecular computation, nanorobotics and biosensing. While the design, modeling and characterization of macroscopic machines is well determined on the basis of kinematics and continuum mechanics, the intrinsic flexibility and stochastic nature of biological systems at the nanoscale make such tasks be highly challenging. 

Continue reading… Sebastian Sensale (Cleveland State University)

Probing the Universe’s expansion and the origin of compact object binaries with multi-messenger astronomy

The synergy between gravitational wave (GW) experiments and optical surveys such as the Dark Energy Survey (DES) and the Dark Energy Spectroscopic Instrument (DESI) is most prominent in the discovery of electromagnetic counterparts to GW events and the application of the standard siren method, which has already enabled several measurements of the Hubble Constant. Our DES follow-up observations of the first binary neutron star merger detected by LIGO/Virgo, GW170817, enabled the discovery of the first optical counterpart to a GW event, and provided information about the origin of the binary.

Continue reading… Antonella Palmese (Carnegie Mellon) [Postponed]

Effects of elasticity on biological assemblies

 Svetlana Morozova, Kathryn Wilcox, Grace Kemerer, Marlee Dingle, Alexandra Grinevich

Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland OH 44106

The elasticity of complex macromolecules is critical for biological function. The mechanical properties of helical polypeptides help the functions of many protein levers and motors, as well as help control the self-assembly of collagen. As the most abundant protein in mammals, collagen is a major structural protein in the extracellular matrix (ECM), which is found in cartilage, hair, skin,

Continue reading… Svetlana Morozova (CWRU)

Acoustic Simulations of Quantum Materials

In the last few years there has been an explosion of new quantum materials, ranging from topology to “twistronics”. Topological materials may be engineered for applications from efficient switches to spin-based computing. “Twistronics” entails the construction of layered materials with emergent electronic and magnetic properties by stacking and twisting individual 2D materials such as graphene. Despite the vast possibilities waiting to be explored, the assembly of such microscopic devices with the necessary precision has proven laborious and expensive. Here we have developed a tangible acoustic analog to these tiny quantum structures!

Continue reading… Jenny Hoffman (Harvard)

Numerical Studies of Screening Mechanisms in Modified Gravity
 
 
In this talk I will present my previous work on screened modified gravity models. Despite the major success of the standard model of cosmology, many questions remain to be answered. In particular, understanding the nature of dark matter and dark energy has been extremely challenging. One possible reason for this is that our understanding of gravity is flawed or incomplete. In this context scalar-tensor theories of gravity have been introduced with hopes of gaining insight into the physics of dark energy and possibly dark matter.

Continue reading… Andrius Tamosiunas (CWRU)

Entrepreneurship: leaving academia in order to improve academia
 
Join Zoom 
 
Have you ever wondered why peer review is the way it is?
 
Andrew completed a PhD in experimental condensed matter physics and a postdoc in soft x-ray spectroscopy before asking that same question and leaving academia to start Publons.com with a mission to improve the peer review system. Publons became a platform that hundreds of thousands of researchers used to keep track of and get credit for peer review activities. It was later purchased by Clarivate (the home of Web of Science).

Continue reading… Special Event: Andrew Preston (Cassyni.com)

Quantum steampunk: Quantum information meets thermodynamics

Thermodynamics has shed light on engines, efficiency, and time’s arrow since the Industrial Revolution. But the steam engines that powered the Industrial Revolution were large and classical. Much of today’s technology and experiments are small-scale, quantum, far from equilibrium, and processing information. Nineteenth-century thermodynamics needs re-envisioning for the 21st century. Guidance has come from the mathematical toolkit of quantum information theory. Applying quantum information theory to thermodynamics sheds light on fundamental questions (e.g., how does entanglement spread during quantum thermalization? How can we distinguish quantum heat from quantum work?) and practicalities (e.g.,

Continue reading… Nicole Yunger Halpern (NIST + Joint Center for Quantum Information and Computer Science + Univ Maryland)

Updated Zoom Link!!!

https://cwru.zoom.us/j/92624627629?pwd=YnNLU2wzL0svRzEzaU9sY24zRklqZz09

Meeting ID: 926 2462 7629
Passcode: biophysics

Title: Synthetic DNA Nanostructures as Platforms for Precise Nanoparticle Organization
 
Assistant Professor
Department of Chemistry
Case Western Reserve University
 
DNA nanotechnology has enabled the ability to build objects and particles at the nanoscale. With the help of a growing repository of DNA self-assembling tools and strategies, it
is possible to create two- and three-dimensional structures, ranging from a few nanometers to micron-scale in size. The cumulative properties of DNA,

Continue reading… Divita Mathur (CWRU)

Title: Exploring Potential Biosignatures in Exoplanet Atmospheres with Current and Future Telescopes

Abstract:  

Exoplanets with radii between those of Earth and Neptune (1.7 – 3.4 Earth radii) have stronger surface gravity than Earth, and can retain a  sizable hydrogen-dominated atmosphere. In contrast  to gas  giant planets, we call these planets gas dwarf planets. Furthermore,  terrestrial planets below the radius valley (< 1.5 Earth radii),  may also have the ability to hold onto hydrogen-dominated atmospheres. Generally, planets with hydrogen/helium dominated atmospheres may be more amenable targets for transmission spectroscopy with current and upcoming space-based missions. In this talk,

Continue reading… Caprice Phillips (Ohio State)

Continue reading… Physics Annual Pumpkin Drop 2022

Spintronics: from angular momentum to information

Paul Haney

Nanoscale Device Characterization Division, NIST

Join Zoom 

Abstract: Spintronics is a field which seeks to utilize the electron spin degree of freedom for developing next generation electronics. Well-established spintronic phenomena have already made a transformative impact on data storage technology in previous decades. Modern spintronics research is focused on utilizing spin-orbit coupling to realize more energy-efficient memory, and applying spintronic devices to next-generation computing designs. In this talk we present a fundamental framework for understanding spintronic device physics from the point of view of angular momentum conservation. 

Continue reading… Paul Haney (NIST)

Talk CANCELLED. Will be rescheduled for Spring

Optimizing High-Penetration Renewable Energy Development

 Widespread use of renewable electricity sources is necessary to address climate change, but their intermittency, geospatial variability, and large land footprints create unique challenges for optimizing deployment while respecting power flow and engineering constraints. In this talk, I will review approaches to plan continental scale systems that are renewable dominant. I will describe the key computational trade-offs and optimization methods that are used to plan land use. Physicists should find these methods accessible. Cost-effective deployment of high-penetration renewable energy systems depends not only on technological and economic considerations but also on market institutions and policy coordination. 

Continue reading… Michael Davidson (University of California, San Diego)

Continue reading… Fall break

Decades of Achievement 

A tribute to eight (plus!) of our physics colleagues having birthdays ending in a zero

This tribute arises not just because of the improbability of so many with the same decadian birthday, but also to more generally celebrate our physics community. This year, one physics faculty member has a 40th birthday, two have their 60th birthday (an historically special physics birthday), three have their 70th, two their 90th, and a couple of others. We highlight their achievements in this mini-symposium with mini-talks, in which each of our decadians will be given an all too short encomium tribute.

Continue reading… Decades of Achievement

Using Machine Learning to Predict Surface Adsorption

Walter Malone

Tuskegee University, 1200 W. Montgomery Rd. Tuskegee, AL 36088

Abstract: The interaction of molecules on metallic surfaces plays an important role in a wide array of technologies from catalysts that remove harmful gases from the atmosphere to light-harvesting devices and devices to store hydrogen.  Modeling these types of interactions, between molecules and a metallic substrate, can cost a large amount of computational time, limiting both the amount of systems one can study and the potential to improve device performance.  To remedy this problem and cut down on computational cost one can employ machine learning techniques. 

Continue reading… Walter Malone (Tuskegee University)

Title:
Cosmology with the Next Generation of Cosmic Microwave Background Experiments
 

Abstract:

Measurements of the polarization of the Cosmic Microwave Background (CMB) are a powerful probe of the composition and evolution of the Universe.  From searching for evidence of inflation shortly after the Big Bang to measuring the optical depth to reionization and probing fundamental particles, precision CMB measurements provide a unique window into many aspects of cosmology. Upcoming balloon- and ground-based experiments will build on technologies demonstrated by current instruments to overcome the challenges presented by increasing sensitivity, mitigating systematic errors, and distinguishing Galactic foregrounds. 

Continue reading… Johanna Nagy (Washington University in St. Louis)

Wigner crystals in atomically thin heterostructures

You Zhou

Materials Science and Engineering, University of Maryland

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Abstract: A Wigner solid — a crystal made entirely of electrons — is a model system for understanding electron correlation physics that underlies a wide range of phenomena, including high-temperature superconductivity and metal-insulator transitions. Despite decades of research, it has been challenging to realize Wigner crystals in the so-called quantum regime where quantum effects dominate over thermal fluctuations. In this talk, I will introduce how atomically thin semiconductors, such as transition metal dichalcogenides,

Continue reading… You Zhou (University of Maryland)

Electron and Muon g-2 in a 2HDM
Abstract: Recent determinations of the electron and muon anomalous magnetic moments point towards a potential discrepancy with respect to the SM prediction. Here we present a flavor conserving Two Higgs Doublet Model that, having non universal leptonic couplings, is capable of explaining all the experimental scenarios available at the moment.  We will also show how the CDF measurement of the W boson mass affects our results. 
 

ZOOM ID: 999 3023 4812, Passcode: PAsems

https://cwru.zoom.us/j/99930234812?pwd=a0tid3VOTzJHTkxBWnNjWmtsNmd5UT09 

Continue reading… Fernando Cornet Gomez (CWRU)

Manipulation of magnetic order and band topology through selective phonon excitation 

Gregory A. Fiete

Department of Physics, Northeastern University 

Abstract: Quantum materials driven out-of-equilibrium by a laser pump offer new opportunities for exploring intriguing quantum phenomena, including electron-correlation behaviors and topological properties of excitations.  After reviewing some recent motivating pump-probe experiments, I will turn to our theoretical studies of driven many-body quantum systems.  I will place particular emphasis on the situation where the laser frequency is chosen to selectively excite particular phonon modes and describe the impact of the non-equilibrium lattice on the electron properties,

Continue reading… Gregory A. Fiete (Northeastern)

Note – Nonstandard time

A tale of two black holes:  Sgr A* and M87*
 
Black holes are one of the most exotic consequences of Einstein’s General Relativity, yet they are also very common, ranging from stellar remnants up to beasts billions of times more massive than our sun.  Despite their reputation as cosmic vacuum cleaners, they actually drive extremely complicated astrophysical systems that can majorly influence their surroundings.   Via their powerful outflows in particular, black holes shape the way the Universe looks today…but not at all times.  Black holes undergo cycles of activity, so to understand their role over cosmological timescales we need to understand not only how they power these outflows from just outside their event horizons,

Continue reading… Sera Markoff (API/GRAPPA, University of Amsterdam)

Title: Pulsar Timing Arrays See Red: Entering the Era of Low-Frequency Gravitational Wave Detection

Abstract: Millisecond pulsars are rapidly rotating neutron stars with phenomenal rotational stability. Pulsar timing arrays world-wide monitor over 100 of these cosmic clocks in order to detect perturbations due to gravitational waves at nanohertz frequencies. These gravitational waves will most likely result from an ensemble of supermassive black hole binaries. Their detection and subsequent study will offer unique insights into galaxy growth and evolution over cosmic time. I will present the most recent NANOGrav and International Pulsar Timing Array datasets and the results of gravitational wave analyses which suggest the presence of a common “red”

Continue reading… Maura McLaughlin (West Virginia University)

Terahertz Spin Dynamics in Dirac Antiferromagnet CoTiO3

Rolando Valdes Aguilar

Department of Physics, Ohio State University

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Abstract.– Recently the study of the interplay between topology and magnetism has started to gain attention. A few materials have been identified to host topologically non-trivial magnons, while many more theoretical proposals continue to be made. One recent example of a potential topological magnetic material is CoTiO3, which purportedly hosts Dirac magnons. We use a combination of time domain THz (TDTS) and magneto-Raman spectroscopies to measure the low energy magnetic spectrum in CoTiO3 and detect the two lowest energy modes,

Continue reading… Rolando Valdés Aguilar (OSU)

Zoom ID: 953 8784 0890  –  Passcode: 975081
 
Zoom link
 
UnNuclear Physics: Conformal Symmetry in Nuclear Reactions

Conformal symmetry plays an important role in quantum field theory and statistical physics. A  nonrelativistic version of the conformal symmetry, also called Schrödinger symmetry, is approximately realized in various physical systems, including neutrons in nuclear physics and ultracold atoms. After going through some basic facts about nonrelativistic conformal field theory, we describe one concrete application of such a theory in the physics of nuclear reactions with several neutrons in the final state.

Continue reading… Dam Son (Chicago)

Title: Neutrino-Assisted Early Dark Energy: Theory and Cosmology

Abstract:  The tension between measurements of the Hubble constant obtained at different redshifts may provide a hint of new physics active in the relatively early universe, around the epoch of matter- radiation equality. A leading paradigm to resolve the tension is a period of early dark energy, in which a scalar field contributes a subdominant part of the energy budget of the universe at this time. This scenario faces significant fine-tuning problems which can be ameliorated by a non- trivial coupling of the scalar to the standard model neutrinos. These become non-relativistic close to the time of matter-radiation equality,

Continue reading… Qiuyue Liang (U Penn)

Some surprising findings in 2D oxides

Walter R. L. Lambrecht

Department of Physics, Case Western Reserve University

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Abstract.–Layered and few-layer 2D oxides have remarkable properties. In this talk I will tell you about two oxides, V2O5 and LiCoO2. In both materials the quasiparticle self-consistent GW method is found to strongly overestimate the optical band gap. This is surprising because  the GW method is usually quite accurate in predicting band gaps.   The question is: what is missing in GW? Is it electron-phonon effects or electron-hole effects on the screening of the screened Coulomb interaction W?

Continue reading… Walter Lambrecht (CWRU)

An Exact Fermionic Chern-Simons-Kodama State in Quantum Gravity

Abstract: The Chern-Simons-Kodama (CSK) state is an exact, non-perturbative wave function in the Ashtekar formulation of classical General Relativity.  In this work, we find a generalized fermionic CSK state by solving the extended gravitational and fermionic Hamiltonian constraints of the Wheeler-DeWitt equation exactly.  We show that this new state reduces to the original Kodama state upon symmetry reduction to FRW coordinates with perturbative fermionic corrections, making contact with the Hartle-Hawking and Vilenkin wave functions of the universe in cosmology.  We also find that when both torsion and fermions are non-vanishing,

Continue reading… Marcell Howard (U Pittsburg)

CANCELED

Light-Matter Interaction in Graphene and Metallic Nanoparticles Nanohybrids  

Mahi R. Singh, 

Department of Physics and Astronomy,  Vanderbilt University, Nashville, USA 

Western University, Ontario, London, Canada N6A 3K7 

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Abstract.–There is considerable interest in light-matter interaction by combining plasmonic materials such as graphene and metallic nanoparticles with quantum dots. Graphene was invented theoretically by Wallace in 1947 [1] and he found that graphene is a gapless material. Later, Wallace and I found additional gapless materials, such as narrow-gap semiconductors which have direct band gaps [2].

Continue reading… (CANCELED) Mahi R. Singh (The University of Western Ontario)

Continue reading… No seminar (Labor Day)

Open- and close-packed oligomers via template-directed assembly of shape-engineered,
lithographically-fabricated nanoparticles

Yiyu Cai

Department of Electrical and Systems Engineering, University of Pennsylvania

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Abstract.—The top-down lithographic fabrication process can produce nanoparticles with well-defined sizes, shapes, and compositions that are not accessible synthetically. Using a template-assisted assembly technique, capillary forces drive the assembly of lithographically-fabricated nanoparticles into open or close-packed structures. The sizes and shapes of the templates control the coordination number, disorder, and location of defects such as voids in the nanoparticle assemblies.

Continue reading… Yiyu Cai (U Penn)

Encoded Silicon Qubits: A High-Performance & Scalable Platform for Practical Quantum Computing

Thaddeus Ladd

HRL Laboratories, LLC

Abstract.—For quantum computers to achieve their promise, regardless of the qubit technology, significant improvements to both performance and scale are required. Quantum-dot-based qubits in silicon have recently enjoyed dramatic advances in fabrication and control techniques. The “exchange-only” modality is of particular interest, as it avoids control elements that are difficult to scale such as microwave fields, photonics, or ferromagnetic gradients. In this control scheme, the entirety of quantum computation may be performed using only asynchronous,

Continue reading… Thaddeus Ladd (HRL labs)

Link to video

Title: Of Elephants and Oscillations

This talk explores next steps in the search for new physics in the neutrino sector.   The discovery of neutrino oscillations has changed the way we think about our model of particle physics.  We must now incorporate tiny neutrino masses into our theory, as well as consider  the possibility of other unexpected properties.   You might ask what a tiny mass particle has to do with elephants?   To learn this, you need to come to the colloquium.

Continue reading… Janet Conrad (MIT)

Topological Twistronics
 
Jennifer Cano 
 
Department of Physics and Astronomy, Stony Brook University
 
Youtube video
 
Abstract.— Twisting van der Waals heterostructures to induce correlated many-body states provides a novel tuning mechanism in solid-state physics, launching the field of “twistronics.” In this talk, we apply twistronics to renormalize the Dirac cone on the surface of a 3D topological insulator, with the goal of realizing tunable interacting topological phases. To achieve this goal, we consider two different platforms: 1) twisted heterostructures in 2D and 3D; and 2) the effect of a moire superlattice potential.

Continue reading… Jennifer Cano (Stony Brook)

Link to video

The 2021 Nobel Prizes in Science

Cyrus Taylor on the prize in physics, Thomas Gray on the prize in chemistry, and George Dubyak on the prize in physiology or medicine.  

Continue reading… Cyrus Taylor (Physics), Thomas Gray (Chemistry) and George Dubyak (Biophysics and Physiology)

Conformal QED in 3d: The Numerical Bootstrap Approach

The IR fixed point of quantum electrodynamics in three dimensions (QED3) is expected to be gapped for a small global symmetry group and strongly interacting for a large one. Concretely, QED3 with the flavor group SU(N) flows to a free theory for small N and to a conformal one for large N, whereas the critical flavor number is suggested to be anywhere between 1 and 10 by various theoretical and computational methods. This phase space of QED3 is very appealing, as it shows analogues of chiral symmetry breaking and confinement and hence can be used as a toy model for the quantum chromodynamics in four dimensions.

Continue reading… Soner Albayrak (Amsterdam U)

Investigations of the first intrinsic topological insulator: MnBi2Te4

William Ratcliff

National Institute of Standards and Technology

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Abstract.—In this talk, I discuss our recent results on the first intrinsic antiferromagnetic topological insulator, MnBi2Te4. In this Van der Waals material, we can control the magnetic state through chemical substitution, as well as through the application of a magnetic field.  These knobs allow us to effect the topology of the band structure and thus the transport.  We apply a number of probes, including transport, susceptibility, neutron scattering,

Continue reading… William Ratcliff (NIST)

Link to video

PT Symmetry

By using complex-variable methods one can extend conventional
Hermitian quantum theories into the complex domain. The result is a huge
and exciting new class of parity-time-symmetric (PT-symmetric) theories
whose remarkable physical properties are currently under intense study by
theorists and experimentalists. Many theoretical predictions have been
verified in recent beautiful laboratory experiments.

Continue reading… Carl Bender (Washington University, St Louis)

POSTPONED due to COVID

Continue reading… Thereza Soares (Federal Univ. of Pernambuco)

The Geometric SMEFT description of curved Higgs Field Space(s)
 
In recent years, the effective field theory approach to the Standard Model, the SMEFT, has been used to study LHC data with ever increasing theoretical precision and sophistication. However, the complexity of this theory lead to several barriers to substantial theoretical progress. In particular, the explosion in the number of parameters in the SMEFT as a function of operator mass dimension, and the technical challenge or reformulating SM predictions consistently into the SMEFT were very serious problems, that called into question the possible success and value of the SMEFT physics program over the long term.

Continue reading… Michael Trott (Niels Bohr Institute)

Shallow and Deep States of Acceptors in GaN: Why Photoluminescence Experiments Do Not Reveal Small Polarons for Defects in Semiconductors

Denis O. Demchenko

Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23220, USA

Youtube video

Abstract.—Currently, only one shallow acceptor (Mg) has been discovered in GaN. Here, using photoluminescence (PL) measurements combined with hybrid density functional theory, we demonstrate that a shallow effective-mass state also exists for the BeGa acceptor. A PL band with a maximum at 3.38 eV reveals a shallow BeGa acceptor level at 113 meV above the valence band,

Continue reading… Denis Demchenko (Virginia Commonwealth)

Link to video

The Borexino Legacy – A Personal Account

Borexino is a large neutrino experiment that contributed ground-breaking measurements of solar and other low-energy neutrinos, thanks to a combination of conceptual simplicity, technical ingenuity, and persistence of almost epical proportions. After almost 15 years of operation at the Laboratori Nazionali del Gran Sasso, Italy, Borexino ended its data taking on October 4, 2021.

In this talk, I will summarize the main science results of Borexino, which include the measurement of all neutrinos emitted by the Sun (solar neutrinos) and of those emitted by the beta radioactivity of the Earth (geo-neutrinos).

Continue reading… Andrea Pocar (University of Massachusetts, Amherst)

Modeling the host galaxies of binary compact object mergers across cosmic time

The first direct detection of a gravitational wave (GW) in 2015 opened a new era for gravitational-wave astrophysics. Since then, more than 70 events have been announced by the LIGO-Virgo-KAGRA collaboration including merging binary black holes (most of them), binary neutron stars, and black hole – neutron star binary systems. GW observations will allow us to address an impressive set of questions in cosmology and astrophysics, such as the nature of dark matter, the nature of gravity, the early Universe, and the different stellar evolution stages currently under debate.

Continue reading… Celeste Artale (University of Padova)

Exploring Many-body Effects on the Dynamics of Optical Excitations  in Low-Dimensional Materials

Diana Qiu, Mechanical Engineering & Materials Science, Yale University

Youtube video

In low-dimensional and nanostructured materials, the optical response is dominated by correlated electron-hole pairs—or excitons—bound together by the Coulomb interaction. Understanding the energetics and dynamics of these excitons is essential for diverse applications across optoelectronics, quantum information and sensing, as well as energy harvesting and conversion. By now, it is well-established that these large excitonic effects in low dimensional materials are a combined consequence of quantum confinement and inhomogeneous screening.

Continue reading… Diana Qiu (Yale)

Link to video

Superoscillations, the Talbot Carpet, and Gauss Sums.

Superoscillations are an interesting phenomenon that appears in different areas, including optics and weak quantum measurements. An important question is whether a superoscillating function maintains its superoscillatory nature when evolved according to specific forms of the Schrodinger equation. In this talk we will consider the evolution of the Dirac comb (infinite sum of deltas) to show how to recover, optically, the generalized quadratic Gauss sums. We will then use the theory of superoscillations to show how such Gauss sums can be asymptotically recovered from the values of the spectrum of any sufficiently regular function with compact support.

Continue reading… Daniele Struppa (Chapman University)

Magnetic quadrupole moment in crystals and nonlinear thermoelectric transport
 
Di Xiao,  Materials Science & Engineering, University of Washington
 
Youtube video
 

Abstract.—The essence of an in-medium formulation of electromagnetism is the use of electric and magnetic multipole moment to characterize the intrinsic charge and current densities, which has wide applications in various fields of physics.  In this talk, I will show that, in the context of solid state physics, the magnetic quadrupole moment is a unifying concept that connects a wide range of magnetoelectric effects in crystals. 

Continue reading… Di Xiao (University of Washington)

Generalized geometry as a natural tool for supergravity

I will describe how the concept of generalized geometry naturally appears in the context of supergravity theories. Using these tools of generalized geometry we can then see some of the odd features of the theory as having a geometric origin.
 
If time permits I will discuss a generalization of these methods developed in M theory. This would be based on a recent joint work with Mark Bugden, Fridrich Valach and Daniel Waldram.

Host: Kurt Hinterbichler

Continue reading… Ondra Hulik (VUB)

Continue reading… No seminar (March Meeting)

Continue reading… No seminar (Spring Break)

Link to video

Machine learning for biological sequence discovery and design
 
Prediction of protein function from sequence is a central challenge. Solving this challenge would enable us to discover new proteins with specific functionality. Experimental breakthroughs allow data on the relationship between sequence and function to be rapidly acquired that can be used to train and validate machine learning models that predict protein function directly from sequence. However, the cost and latency of wet-lab experiments require methods that find good sequences in few experimental rounds, where each round contains large batches of sequence designs.

Continue reading… Lucy Colwell (Cambridge University)

Colliders and cosmic origin stories

The foundational origins of diverse cosmic phenomena remain enduring enigmas. The LHC decisively tests longstanding cosmological origin hypotheses for dark matter such as supersymmetry, and mass genesis via the Higgs mechanism. Meanwhile, muons from high-energy cosmic rays are the archetypal ‘who ordered that?’ surprise and fittingly, recent muon measurements could be challenging standard paradigms again. The ATLAS experiment confronts these puzzles while pioneering innovations including photon collisions, forward detectors, heavy-ion beams, and unconventional datasets. Beyond colliders, quantum sensing progress enables next-generation haloscopes to illuminate axion-like origins of dark matter above microwave frequencies.

Continue reading… Jesse Liu (Cambridge)

Atomistic Topological Electrodynamics

Zubin Jacob, School of Electrical and Computer Engineering, Purdue University, Indiana, U.S.A.

Youtube video

zjacob@purdue.edu, www.electrodynamics.org

Abstract.—Over the last decade, the concept of Dirac matter has emerged to the forefront of condensed matter physics. Prominent examples include the physics of the Dirac point in Graphene, Weyl points in topological semi-metals (TaAs) and edge states in topological insulators (Bi2Te3).  These phases of matter are a playground for studying effects related to topology and spin-1/2 Dirac Hamiltonians.

Continue reading… Zubin Jacob (Purdue)

Link to video

Patterns on the Sky: Galaxy Dynamics Edition
 
Like planets, galaxies are observed to obey a number of strict rules that govern their dynamics. Unlike planetary systems, this behavior is not explicable with known physics – hence the dark matter problem. I will describe progress in quantifying the relations obeyed by extragalactic systems, which have deep implications of fundamental physics. 

Continue reading… Stacy McGaugh (CWRU Astronomy)

Special time 11:00 am ET!!

Precision measurements of the positive muon lifetime and muonic hydrogen atom lifetime

I will describe the results from two sister experiments — MuLan and MuCap — conducted at at Paul Scherrer Institute (PSI) in Switzerland. In the MuLan experiment the positive muon lifetime was measured to +/-1.0 ppm precision and used to extract the Fermi Constant G_F to +/-0.6 ppm precision. In the MuCap experiment the muonic hydrogen atom lifetime was measured to +/-10 ppm precision and used to extract the induced pseudoscalar coupling g_p of the proton weak interaction to +/-7%.  

Continue reading… Tim Gorringe (U Kentucky)

Skyrmions in Blue Phases of Chiral Liquid Crystals

Igor Muševiča,b

a Condensed Matter Physics Department, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia

b Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia

Youtube video

Abstract.–Skyrmions are topologically protected, vortex-like formations of a field that cannot be removed by any smooth transformation and emerge in a range of fundamentally different, either quantum or classical systems, from spin textures, to chiral ferromagnets and chiral complex fluids.

Continue reading… Igor Musevic (Institute Josef Stefan)

Video here

 
The continuing risk of nuclear war and how physicists, acting as citizen-scientists, can help reduce it
 
The public, including most physicists, and Congress, assume that, since the Cold War ended, the danger of nuclear war must have diminished to a negligible level. The danger of deliberate nuclear use has diminished but the danger of accidental nuclear war may be increasing. US and Russian strategic missiles remain in a launch-on-warning posture in an era when hackers have penetrated some of our supposedly most secure computer systems. Both Russia and the United States have halted their nuclear reductions at levels an order of magnitude higher than required by minimum deterrence.

Continue reading… Frank von Hippel (Princeton)

Missing Scalars at the Cosmological Collider

Light scalar fields typically develop spatially varying backgrounds during inflation. Very often they do not directly affect the density perturbations, but interact with other fields that do leave nontrivial signals in primordial perturbations. In this sense they become “missing scalars” at the cosmological collider. We study potentially observable signals of these missing scalars, focusing on a special example where a missing scalar distorts the usual oscillatory features in the squeezed bispectrum. The distortion is also a useful signal distinguishing the de Sitter background induced thermal mass from a constant intrinsic mass.

Continue reading… Qianshu Lu (Harvard)

All-solid-state lithium-ion batteries: Challenges and opportunities

Angelique Jarry, Senior Technology Manager – Battery

Moses Lake Industries, Portland, Oregon, ajarry@mlindustries.com

Join Zoom

Abstract.—All-solid-state batteries (SSBs) are widely seen as the next-generation energy storage system due to their inherent safety and other benefits. However, further development of SSBs is still impeded by the current lack of understanding/engineering at the interfaces formed upon cycling. Recent progress in the development of characterization surface techniques using synchrotron radiation or lab sources has enabled major scientific advancements toward this understanding. The challenges and approaches of transitioning from the standard liquid electrolyte-based lithium-ion batteries to all-solid-state batteries with multi-electron transfer will be presented.

Continue reading… Angelique Jarry (Moses Lake Industries Inc.)

Comet Fading Begins Beyond Saturn

Video here
 
The discovery probability of long-period comets (LPCs) passing near the Sun is highest during their first passage and then declines, or fades, during subsequent return passages. Comet fading is largely attributed to devolatilization and fragmentation via thermal processing within 2-3 au of the Sun (1 au being the Earth-Sun distance). Here our numerical simulations show that comet observing campaigns miss vast numbers of LPCs making returning passages through the Saturn region (near 10 au) because these comets fade during prior, even more distant passages exterior to Saturn and thus elude detection.

Continue reading… Nathan Kaib (University of Oklahoma)

Effective Field Theory and the Geometry of Electroweak Symmetry Breaking
 
There are two canonical approaches to treating the Standard Model as an effective field theory: the Standard Model EFT (SMEFT), respecting the full electroweak gauge symmetry, and the Higgs EFT (HEFT), respecting only electromagnetism. Of these, SMEFT has become the predominant framework for interpreting LHC Higgs data and exploring the systematics of effective field theory. This raises a number of questions: Is HEFT relevant in light of current data? What types of UV physics (if any) require HEFT, rather than SMEFT? Is SMEFT enough? In this talk,

Continue reading… Nathaniel Craig (UCSB)

Postponed!

TBA. 

Host: PURMS

Continue reading… ***POSTPONED (rescheduling TBD): Andrew Preston (Cassyni)

***Postponed Due to Weather***

The 2021 Nobel Prizes in Science

Cyrus Taylor on the prize in physics, Thomas Gray on the prize in chemistry, and George Dubyak on the prize in physiology or medicine.  

Continue reading… ***POSTPONED DUE TO WEATHER*** Cyrus Taylor (Physics), Thomas Gray (Chemistry), George Dubyak (Biophysics and Physiology)

Better Neutrinoless Double Beta Decay through Biochemistry

The goal of future neutrinoless double beta decay experiments is to establish whether neutrino is its own antiparticle, by searching for an ultra-rare decay process with a half life that may be more than 10^27 years.  Such a discovery would have major implications for cosmology and particle physics, but requires ton-scale detectors with backgrounds below 1 count per ton per year.  This is a formidable technological challenge that has prompted consideration of unconventional solutions.  I will discuss an approach being developed within the NEXT collaboration: high pressure xenon gas time projection chambers augmented with single molecule fluorescent imaging-based barium tagging.

Continue reading… Benjamin Jones (UT Arlington)

Postponed!

TBA. 

Host: Walter Lambrecht

Continue reading… Jonathan Albert Fan (Stanford)

The Phantom Menace: Modified Gravity as an Alternative to the Planet Nine Hypothesis

An exciting development in outer solar system studies is the discovery of a new class of Kuiper belt objects with orbits that lie outside that of Neptune and have semimajor axes in excess of 250 A.U. The alignment of the major axes of these objects and other orbital anomalies are the basis for the Planet Nine hypothesis that an undiscovered giant planet orbits the sun at a distance of around 500 A.U. We show that a modified gravity theory known as MOND (Modified Newtonian Dynamics) provides an alternative explanation for the observed alignment,

Continue reading… Harsh Mathur (CWRU)

Superconductivity at the oxide-insulator/KTaO3 interface and electric-field control of magnon spin current in Cr2O3

Changjiang Liu, Department of Physics, University of Buffalo

Youtube video

Abstract. — Oxide material system is an ideal playground for uncovering new physical phenomena owing to the strong interactions between electron spins, charges, and lattices. In this talk, I will first present the recent discovery of two-dimensional superconductivity at the oxide-insulator/KTaO3 (111) interfaces. The superconducting transition temperature Tc reaches 2.2 K, which is about one order of magnitude higher than that found in the widely studied LaAlO3/SrTiO3 system.

Continue reading… Changjiang Liu (University at Buffalo)

Friendship in the Axiverse

The Axiverse is a scenario in which axion-like particles are distributed over many orders of magnitude in mass and interact with one another through a joint potential. In this talk, I will show how non-linearities in this potential lead to a new type of resonant energy transfer between “friendly” axions with nearby masses. This resonance generically transfers energy from axions with larger decay constants to those with smaller decay constants, leading to a multitude of signatures. These include enhanced direct detection prospects for a resonant pair comprising even a small subcomponent of dark matter,

Continue reading… David Christopher Cyncynates (Stanford)

Continue reading… No seminar (MLK)

Continue reading… No seminar

Michelson Postdoctoral Prize Lecture 4

2D materials discovery and design

With the tools discussed in the previous lectures, we can now aim at materials discovery and design.
Thanks to the combination of high-performance computing resources and software for the management of high-throughput calculations, one can now study thousands of materials in relatively short timescales. Databases of material properties computed from first-principles have flourished over the past few years. After introducing a database of around 2000 2D materials found to be exfoliable from existing 3D compounds, I will discuss how one can investigate complex mechanisms such as electron-phonon scattering on the scale of many materials.

Continue reading… Thibault Sohier (CNRS, Montpellier)

Michelson Postdoc Prize Lecture 3 
 

2D electron-phonon physics from first-principles

Reduced dimensionality has consequences for phonons and electron-phonon interactions. So does the use of gates to dope the layer within the typical field-effect setups used in experiments. In this second lecture, I will describe density-functional perturbation approaches developed to explore those consequences. First-principles results will be supported by analytical models and intuitive explanation of the mechanisms at play. I will first present the general physics of polar-optical phonons, relevant for any semiconductor with more than one element. The energetics and electron-phonon interactions associated with those modes strongly depends on dimensionality and the environment.

Continue reading… Thibault Sohier (CNRS, Montpelier)

Michelson Postdoc Prize Lecture 2

Graphene case study: why is it so good, and can it be even better?

Graphene is the first and most famous 2D material. Many of the prospects and challenges of the 2D realm were first raised by studying this material. It is exceptional on many levels, including its ability to conduct electrons with very little resistance from the phonons. In a journey towards modelling and engineering phonon-limited transport in 2D materials, it is a natural starting point.
This first lecture will be an in-depth study of transport in graphene.

Continue reading… Thibault Sohier (CNRS, Montepellier)

Michelson Postdoc Prize Lecture 1

Modelling and engineering of phonon-limited transport in 2D materials from first-principles

2D materials have raised tremendous interest in the condensed-matter community. They have shown fascinating fundamental physics, from electronic transport to topology; along with exciting technological prospects, from transistors to integrated optoelectronics. Many applications rely on the ability of a material to conduct electrons efficiently. At room temperature, the main intrinsic limiting factor is electron-phonon scattering. A deep understanding of phonon-limited transport, along with predictive first-principles models, are thus key to designing high-performance, energy-efficient devices. As fabrication and characterization techniques improve,

Continue reading… Thibault Sohier (CNRS, Montpellier)

Of Rice and Men: Jamming of inert and active matter

Amy Graves

Dept. of Physics and Astronomy, Swarthmore College

Youtube video

Abstract. — Grain, sand, colloids, living cells and pedestrians can behave dramatically by suddenly solidifying into a disordered “jammed” structure.   Much has been learned about jamming in last two decades. Our research asks what is new and different when these particles are in contact with a fixed framework, like a lattice of diminutive obstacles or “pins”.  In a first project on inert matter,

Continue reading… Amy Graves (Swarthmore College)

Enabling novel light phenomena at the subwavelength scale

By nano-structuring materials at length scales smaller than the wavelength of light, one can create effective materials, exhibiting optical properties unparalleled in any naturally occurring materials. This talk will present our work in three areas of research that have recently been of particular interest to the nanophotonics community: plasmonics, topology, and artificial intelligence. First, via plasmonics, one can spatially confine light by orders of magnitude compared to light confinement in regular materials; conventional Maxwell’s equations are no longer suitable for modelling this regime.

Continue reading… Marin Soljacic (MIT)

Clock Effects as explanation for the flat-rotation curve problem

The flat-rotation curve problem of spiral galaxies is commonly addressed by either Modified Newtonian Dynamics (MOND) or Dark Matter models (DM). Both approaches interpret the observations of shifted spectra as physical orbital velocities by the Lorentz Doppler formula, velocities which diverge from the expectations from luminous mass at large radii.  Both approaches require new physics. We present a new relativistic approach, in which the Doppler shifted frequencies are not interpreted as physical velocities, but rather as frame effects due to our observation point in a rotating Milky Way galaxy. 

Continue reading… Sophia Cisneros (Denver)

Perovskite-Based Photovoltaics for Applications in Space

Lyndsey McMillon-Brown

NASA Glenn Research Center

Youtube video

Abstract. — In support of a sustainable human-lunar presence there is a need for very large (>100 kW) and high-voltage-capable solar arrays, estimated to cost over $150M.  Perovskite-based thin film photovoltaics offer substantial advantages over state-of-the-art solar arrays from the perspective of manufacturing of large arrays.  Many of the challenges perovskite solar cells experience in terrestrial operations (e.g., degradation caused by moisture and oxygen exposure) are not applicable in long-term space applications,

Continue reading… Lyndsey McMillon-Brown (NASA Glenn)

Link to Video 

Can wobbling muons probe physics beyond the standard model? Fermilab’s Muon g-2 Run 1 results.

On April 7th 2021, Fermilab’s Muon g-2 experiment announced its first results of the precision measurement of the anomalous muon magnetic moment based on its 2018 Run-1 dataset. These results align with the Brookhaven National Laboratory experimental value and the combined values increases the tension between experiment and theory from 3.7 to 4.2 sigma. This talk will give an overview of the Fermilab Muon g-2 experiment, discuss the steps necessary to precisely measure wobbling muons,

Continue reading… Jessica Esquivel (Fermilab)

Renormalization Group Flows on Line Defects 

In this talk, we will consider line defects in d-dimensional CFTs. The ambient CFT places nontrivial constraints on renormalization group flows on such line defects. We will see that the flow on line defects is consequently irreversible and furthermore a canonical decreasing entropy function exists. This construction generalizes the g theorem to line defects in arbitrary dimensions. We will demonstrate this generalization in some concrete examples, including a flow between Wilson loops in 4 dimensions, and an O(3) bosonic theory coupled to impurities with large isospin.

Host: Kara Farnsworth

Continue reading… Avia Raviv-Moshe (SCGP)

First principles simulations of optically activated processes in materials and molecules

Marco Govoni1,2

1Materials Science Division & Center for Molecular Engineering, Argonne National Laboratory

2Pritzker School of Molecular Engineering, University of Chicago

Abstract. —The robust description of excited states for complex heterogeneous systems is the cornerstone of a computational framework that enables the modelling of materials for sustainable energy and quantum information science applications [1]. I will present the simulation of optically activated processes in materials using a hierarchical modeling approach that relies on the combination of density functional theory,

Continue reading… Marco Govoni (Argonne National Laboratory)

Link to video

Using magnetic tunnel junctions to compute like the brain

Computers, originally designed to do precise numerical processing, are now widely used to do more cognitive tasks. These include categorical challenges like image and voice recognition, as well as robotic tasks like driving a car and making real-time decisions based on sensory input. While the human brain does not do precise numerical processing well, it excels at these other tasks, leading researchers to look to the brain for inspiration on efficient ways to engineer cognitive computers. Of particular interest are energy and space optimization.

Continue reading… Mark Stiles (NIST)

The Newman-Penrose Map and the Classical Double Copy

Gauge-gravity dualities are powerful tools for understanding aspects of quantum gravity. Considerable progress has been made in relating scattering amplitudes in certain gravity theories to those in gauge theories—a correspondence which is sometimes called the “double copy.” Recently, double copies have also been realized in a classical setting as maps between exact solutions of gauge theories and gravity. In this talk, I will discuss a novel map between a certain class of real, exact solutions of Einstein’s equations, and self-dual solutions of the flat-space vacuum Maxwell equations. This map,

Continue reading… Gabriel Herczeg (Brown)

Theoretical Predictions of Superconducting and Superhard Materials

Eva Zurek, Department of Chemistry at the University at Buffalo

Youtube video

Abstract.—The pressure variable opens the door towards the synthesis of materials with unique properties, e.g. superconductivity, hydrogen storage media, high-energy density and superhard materials. Under pressure elements that would not normally combine may form stable compounds or they may adopt novel s toichiometries. As a result, we cannot use our chemical intuition developed at 1 atm to predict phases that become stable when compressed. To facilitate the prediction of the crystal structures of novel materials,

Continue reading… Eva Zurek (University at Buffalo)

Link to video

Using the Higgs boson to search for dark sector particles

The discovery of the Higgs boson has enabled a new and rich experimental program that includes using the Higgs boson to search for new particles. In this talk, I will discuss searches for dark sector particles in the decays of the Higgs Boson and the prospects for the LHC Run3.

Continue reading… Ketevi Assamagan (Brookhaven National Lab)

What can effective quantum mechanics do for you?

In this talk I will explain how a stubborn curiosity about boundary conditions in quantum mechanics led to the development of a long-distance effective approach to describing quantum mechanical systems, borrowing heavily from the ideas of effective field theory. I will describe how this approach is applied to yield an effective (quantum defect) theory of positronium. This is pertinent because of a recent 4.2 σ discrepancy between the theory of bound-state quantum electrodynamics (QED) and a recent transition frequency measurement by Gurung et al. (2020 & 2021). The effective theory that I will discuss not only provides an accurate and economical means to fit the positronium spectrum,

Continue reading… David Jacobs (Norwich University)

Self-Hybridization and Tunable Magnon-Magnon Interactions in Layered Antiferromagnets

Department of Physics and Astronomy, Wayne State University

Youtube video

Abstract.– Within antiferromagnetic materials and metamaterials, magnons, with frequencies spanning tens of GHz to THz frequencies exist at all wavenumbers.  This availability of ultrafast magnons is largely responsible for the magnetism community’s recognition that antiferromagnets should play an active role in next-generation electronics, magnetics, and opto-electronics [1,2].  In this work, we examine, through modeling and experiment, magnons in layered antiferromagnetic materials. Of particular interest are van der Waals magnets,

Continue reading… Joseph Sklenar (Wayne State University)

This talk will be rescheduled for another semester

Continue reading… Randall McEntaffer (Penn State University) POSTPONED

Continue reading… No Seminar (Fall break)

Is Our Universe the Remnant of Chiral Anomaly in Axion Inflation?

Modern cosmology has been remarkably successful in describing the universe from a second after the Big Bang until today. However, its physics before that time is still much less certain. It profoundly involves particle theory beyond the Standard Model to explain long-standing puzzles: the origin of the observed matter asymmetry, and massive neutrinos, as well as the particle physics of dark matter and cosmic inflation. In this talk, I will explain that a new framework based on embedding axion-inflation in left-right symmetric gauge extensions of the SM can possibly solve and relate these seemingly unrelated mysteries of modern cosmology.

Continue reading… Azadeh Maleknejad (CERN)

Interplay of Topology and Geometry in Fractional Quantum Hall Liquids

Kun Yang

Department of Physics, Florida State University

Youtube video

Abstract.– Fractional Quantum Hall Liquids (FQHL) are the ultimate strongly correlated electron systems, and the birth place of topological phase of matter. Early theoretical work has emphasized the universal or topological aspects of quantum Hall physics. More recently it has become increasingly clear that there is very interesting bulk dynamics in FQHL, associated with an internal geometrical degree of freedom, or metric. The appropriate quantum theory of this internal dynamics is thus expected to take the form of a “quantum gravity”,

Continue reading… Kun Yang (Florida State University)

Crackdown on Academic Collaboration with China Harms American Science

Academic collaboration with China was once encouraged by the US government and universities. As tension between the two countries rises rapidly, those who did, especially scientists of Chinese descent, are under heightened scrutiny by the federal government. Law enforcement officials consider collaborating with Chinese colleagues “by definition conveying sensitive information to the Chinese.” In 2015, I became a casualty of this campaign despite being innocent. “China Initiative” established by the Justice Department in 2018 has resulted in numerous prosecutions of university professors for alleged failure to disclose China ties.

Continue reading… Xiaoxing Xi (Temple University)

Biological signals and cell signaling pathways – A computational approach.

Type I interferons are used effectively in the treatment of Hepatitis C by activating a cascade of interferon-stimulated genes with antiviral properties. The signaling cascade involves the binding of IFN to the two subunits of the IFN receptor, IFNAR1 (R1) and IFNAR2 (R2), to form a ternary complex. The kinases – Jak’s and Tyk’s – bound to the cytoplasmic domains of receptor subunits become phosphorylated, which further phosphorylates STAT (p-STAT). Dimers of p-STAT migrate to the nucleus to initiate the transcription of a large number of genes.

Continue reading… Chitra Nayak (Tuskegee University)

Cosmology from weak lensing and galaxy clustering in the Dark Energy Survey
 
Galaxy cosmic surveys such as the Dark Energy Survey are a powerful tool to extract cosmological information. In particular, the combination of weak lensing and galaxy clustering measurements, usually known as 3x2pt, provides a potent and robust way to constrain the parameters controlling the structure formation in the late Universe. In this talk I will give an overview of the results and methods of Dark Energy Survey Y3 3x2pt cosmological analysis, focusing specially on the galaxy-galaxy lensing probe, which is the cross-correlation of the shapes of source background galaxies with lens foreground galaxy positions.

Continue reading… Judit Prat (U Chicago)

Exploring the Limits of Spin Triplet Superconductivity

Nicholas P. Butch

NIST Center for Neutron Research & University of Maryland, College Park

Youtube video

Abstract.– At temperatures below 1.6 K, novel spin-triplet superconductivity is found in the compound UTe2. This unusual form of superconductivity features intriguing properties, such as multiple order parameters, time-reversal symmetry breaking, and in-gap chiral surface states. Other very unusual features are revealed in high magnetic fields – a very large critical field of 35 T that coincides with a metamagnetic transition and, at even higher fields,

Continue reading… Nicholas Butch (NIST)

Link to video

Tidal Disruption Events: Using A Violent Demise to study Extreme Environments

A Tidal Disruption Event (TDE) occurs when a star wanders too close to a supermassive black hole (SMBH) and is unbound by tidal forces.  Studying TDEs can allow us to learn not just about the event itself, but also about the outflows and shockwaves they create and the environment surrounding a previously quiescent black hole.  In this talk, I will give an overview of TDE observations, primarily focusing on the radio, and a summary of where the field stands today. 

Continue reading… Yvette Cendes (Harvard-Smithsonian Center for Astrophysics)

Phenomenal cosmic insights; itty bitty recoils — CEvNS and the COHERENT experiment

Coherent elastic neutrino-nucleus scattering (CEvNS) is the neutral current process by which an incident neutrino interacts (coherently) with a whole nucleus and causes a *teensy* nuclear recoil (the only experimental observable).  This Standard Model process was predicted more than 40 years ago, but it was unambiguously observed for the first time only after decades of advancement enabled the detection of such small recoils.  In 2017, the COHERENT experiment made the first CEvNS observation on CsI at Oak Ridge National Laboratory, then followed up with CEvNS measurements on a second nuclear target (Ar) in 2020. 

Continue reading… Rebecca Rapp (CMU)

SCSAM: Materials Analysis Across Disciplines

Jennifer L.W. Carter

Department of Materials Science and Engineering, Case School of Engineering

Youtube video

Abstract. — The ages of man are benchmarked by the materials we have advanced, from the stone age to the silicon age; there is no engineering progress in society without first advancing the materials needed to meet those challenges. The National Academy of Engineers has identified fourteen societal grand challenges that fall into four cross-cutting categories: sustainability, health, security, and joy of living [1].

Continue reading… Jennifer L.W. Carter (CWRU)

Link to video

Eunice Foote, CO2 atmospheric warming and climate – a once forgotten Climate Science Pioneer.

While James Tyndall is credited as discovering the Greenhouse effect, Eunice Newton Foote conducted experiments three years before Tyndall’s published work and was the first to experimentally demonstrate the warming potential of CO2 and water vapor, and to suggest linkages between these gases, atmospheric warming and climate change by inference to past warmer climates during Deep Time. 
 
This talk will discuss the historical context of Eunice Newton Foote’s once lost work and her role in the beginnings of climate science.

Continue reading… Joseph Ortiz (Kent State University)

Hamiltonian Truncation and the Future of Numerical Quantum Field Theory

Hamiltonian truncation is a  non-perturbative approximation of a quantum system based on projecting the Hilbert space onto a finite-dimensional subspace and numerically diagonalizing the Hamiltonian on the subspace. This method has recently attracted renewed interest, but is still far less developed than lattice quantum field theory. In this talk, I will describe recent work that aims to advance Hamiltonian truncation as a tool for precision numerical studies of quantum field theory. First, I discuss the effective field theory of Hamiltonian truncation, which gives a systematic understanding of the errors made in the truncation and how to correct for them.

Continue reading… Markus Luty (UC Davis)

Plasmonic Metastructures and Bio-Assemblies: Chirality, DNA-origami, and hot electrons

Alexander O. Govorov

Department of Physics and Astronomy, Ohio University, Athens, USA; govorov@ohio.edu

Abstract.– Plasmonic nanostructures and metamaterials are very efficient at the absorption and scattering of light. The studies to be presented in this talk concern special designs of hybrid nanostructures with electromagnetic hot spots, where the electromagnetic field becomes strongly enhanced and spatially concentrated. Overall, plasmonic nanostructures with hot spots demonstrate strongly amplified optical and energy-related effects, and this talk will review some of such phenomena.

Continue reading… Alexander Govorov (Ohio University)

How well does galaxy clustering constrain cosmology?

On the LCDM cosmology, dark matter collapses into virialise objects called haloes. The abundance and distribution of these haloes are a direct consequence of the cosmology of the Universe. By constraining the dark matter halo clustering, we could also constraint the cosmology from our Universe. Since dark matter haloes can not be observed, we need to use galaxies to trace them.

In this talk, I will present a new method that we develop capable of constraining cosmological information from the redshift space galaxy clustering.  We use the scaling of cosmological simulations and the SubHalo Abundance Matching extended (SHAMe) empirical model to produce realistic galaxy clustering measurements over a wide range of cosmologies.

Continue reading… Sergio Contreras (DIPC)

Phononic Frequency Combs for Material Science and Engineering

Adarsh Ganesan

National Institute of Standards and Technology

Youtube video

Abstract. — Phononic frequency combs (PFC) are the mechanical analogs of celebrated photonic frequency combs. These represent a newly documented physical phenomenon in the well researched physical domain of mechanical resonators [1]. The emergence of PFC is mediated by nonlinear modal coupling. Through a series of experiments with mechanical devices, various features of PFC have now been identified. These include drive parameters for comb operation,

Continue reading… Adarsh Ganesan (NIST)

Link to video

Facilitating thinking and learning in and beyond the physics classroom

I will discuss, using my research in physics education, how research can be used as a guide to develop curricula and pedagogies to reduce student difficulties and for making physics equitable and inclusive. My research has focused on improving student understanding of introductory and advanced concepts, for example, in learning quantum mechanics.  We are developing research-validated learning tools such as tutorials and peer instruction tools that actively engage students in the learning process.  I will first discuss how we evaluate the effectiveness of these tools using a variety of methodologies.

Continue reading… Chandralekha Singh (University of Pittsburgh)

Observing the Time-Variable mm-Wave Sky with SPT-3G
 
High-angular-resolution cosmic microwave background experiments provide a unique opportunity to conduct a survey of time-variable sources at millimeter wavelengths, a population which has primarily been understood through follow-up measurements of  detections in other bands. Here I report and expand on the first results of an astronomical transient survey (https://iopscience.iop.org/article/10.3847/1538-4357/ac06a3) with the South Pole Telescope (SPT) using the SPT-3G camera to observe 1500 square degrees of the southern sky. I will also discuss on-going efforts to monitor active galactic nuclei and provide near real-time alerts of transient events including stellar flares,

Continue reading… Allen Foster (CWRU)

Continue reading… No Seminar (Labor Day)

Self-similar solutions to the asymptotic evolution of Rayleigh-Taylor and Richtmyer-Meshkov instabilities and its dependence on the initial conditions

Hydrodynamic instabilities are ubiquitous in nature and technological
applications. In this presentation, an introduction to the basics of the classical
hydrodynamic instabilities – Rayleigh-Taylor, Richtmyer-Meshkov, and Kelvin-
Helmholtz – will be given. The dynamics of those instabilities, from the linear
stage to the fully non-linear, multimode, turbulent mixing, will be described.
The Rayleigh-Taylor and Richtmyer-Meshkov instabilities dependence on
the initial perturbation spectrum is analyzed using a mean-field modal model.
Using the model,

Continue reading… Yonatan Elbaz (NRCN/CWRU)

Dynamics of topological defects in freely floating smectic liquid crystal films and bubbles

Amine Missaoui

Department of Physics, CWRU

Youtube video

Abstract.– Topological defects have a significant influence on the macroscopic properties of materials. In this context liquid crystals (LC) are useful as model systems because it is relatively easy to create and study well-controlled LC topological defects. We study the annihilation of topological defect pairs in the quasi-two-dimensional geometry of freely suspended smectic films. We prepare pairs with opposite topological charges and retrieve the interaction mechanisms from their trajectories.

Continue reading… Amine Missaoui (CWRU)

Magnetism and superconductivity in rhombohedral trilayer graphene
 
Andrea Young
 
Department of Physics, UC Santa Barbara
 
Youtube video
 
Abstract.– I will introduce the electronic structure of rhombohedral trilayer graphene, which hosts a saddle point van Hove singularity.  Experiments probing thermodynamic density of states and electronic transport show that as the density is tuned towards the van Hove singularity, a cascade of ferromagnetic transitions occurs between states with broken spin and/or valley symmetries, including “half-metal” and “quarter-metal” states with a variety of Fermi surface topologies.  Unexpectedly, we find superconducting states in the proximity of several of these magnetic transitions,

Continue reading… Andrea Young (UC Santa Barbara)

Over the last semester, faculty from Physics and three other departments and more than 50 students participated in a new course on Quantum Computing, Information, and Devices. Please join us Tuesday, May 18, from 12 PM to 2 PM for the final capstone of the course: a virtual poster session presenting the outcomes of the students’ group projects. With topics ranging from quantum gate implementations, to quantum algorithms, to quantum error correction codes, these presentations will bring together the mathematics, physics, engineering, and computer science dimensions of the field. Hosted on Gather.town, the session will allow you to browse posters,

Continue reading… Quantum Computing, Information, and Devices Poster Session

Monday, May 3rd we will have our last Q&A of the semester. This Q&A is open to undergrads, graduate students, and post-docs, and is intended to serve as an intimate space where the audience can ask questions to better understand the speaker and their background. 
 
Next week we will host Dr. Alexis Plascenia Contretas, a post-doc working alongside Professor Pavel Fileviez Pérez here at Case. Dr. Plascenia Contretas received a bachelor’s in engineering physics from el Tecnológico de Monterrey, a masters in physics from the University of Sussex, and a physics Ph.D. from Durham University. At Case, Alexis investigates the nature of dark matter,

Continue reading… Q&A with Dr. Alexis Plascencia Contreras

Link to video

 
Extraterrestrial Life: Are We the Sharpest Cookies in the Jar?
 

The search for extraterrestrial life is one of the most exciting frontiers in Astronomy. First tentative clues were identified  close to Earth in the form of the weird interstellar object `Oumuamua. Our civilization will mature once we find out who resides on our cosmic street by searching with our best telescopes for unusual electromagnetic flashes, industrial pollution of planetary atmospheres, artificial light or heat, 

Continue reading… Avi Loeb (Harvard)

Nuclear Levels as Analyzers of High Energy Interactions

The theme of the talk is measurement, and how a clever experiment can eliminate the need for complex, model-dependent analysis.

My thesis demonstrated the ability of using the excitation of Carbon to its first excited state as a target to select diffractive high energy interactions. In this talk, I will describe unpublished results from an experiment performed at Brookhaven National Laboratory where this technique was used to study properties of the A1 meson, a diffractively produced excited state of the pion. The results are in (three sigma) tension with the Particle Data Group’s estimate for the A1 mass.

Continue reading… Don Scipione (ACMEX)

Dr. Jose Leo Bañuelos, a professor at the University of Texas, El Paso. Dr. Bañuelos received his B.S. and Ph.D. from New Mexico State University, before completing a post-doc in the Chemical Sciences Division at Oak Ridge National Laboratory. At UTEP, his group, the NICE2 Lab (Nanomaterials, Interfaces, and Confinement for Energy & the Environment Laboratory), uses x-ray and neutron scattering structural and spectroscopic techniques to study surface and nanoconfinement effects on the molecular-scale properties of complex fluids and soft matter systems. He will share his journey through higher education as a Latino man and answer audience questions regarding his research and experiences.

Continue reading… Q&A with Dr. Jose Leo Bañuelos – Monday April 26th

Elucidating the Effects of Magnetism in Topological Materials

Matthew J. Gilbert

Department of Electrical and Computer Engineering & Department of Physics, University of Illinois, Urbana, IL

Youtube video

Abstract.– For many years, topological materials have been the subject of great interest from condensed matter experimentalists and theorists. While there is a continued push to predict and measure new topological phenomena there exists a large class of “well-known” topological materials, or those that have been thoroughly characterized for their basic topological properties, that may serve as a testbed for new physics and applications by utilizing the inherent properties of these topological materials.

Continue reading… Matthew Gilbert (UIUC)

Link to video

Helping students develop a growth mindset

Instructors often focus on content and pedagogical approaches to improve student engagement and learning in physics courses. However, students’ motivational characteristics can also play an important role in their engagement and success in physics. For example, students’ views about whether intelligence in physics is “fixed” or “malleable,” their sense of belonging in a physics class, and their self-efficacy can affect engagement and learning. I will discuss prior research studies that show how different types of interventions (e.g., social belonging and growth mindset) have improved the motivation and learning of all students,

Continue reading… Emily Marshman (Community College of Allegheny County)

Flavour Anomalies: Lepton-Quark Unification at the TeV scale
 
Abstract:
 

Deviations from the standard model predictions in the semileptonic decays of the B mesons have been reported by the LHCb and the B-factories over the last decade. Among them, strikingly, a deviation of 3.1 sigma in one of the cleanest observables, R(K), was recently announced by the LHCb. In this talk we review the status of these so-called flavour anomalies in the light of the data at face value and the upcoming experimental measurements. We present the simplest theory where one can understand the unification of matter (quarks and leptons) and show how these anomalies can be naturally accommodated in its context and discuss what are their implications regarding other predictions. 

Continue reading… Clara Murgui (Caltech)

Quantum Hall Meets Superconductivity: Interference of Chiral Andreev Edge States

Harold Baranger, Department of Physics, Duke University

Youtube video

Abstract.— The boundaries between distinct quantum states have attracted increasing interest as a setting for novel topological and correlated phenomena. I will discuss our work on the interface between two prototypical phases of electronic matter with conceptually different ground states: the integer quantum Hall insulator and the s-wave superconductor. Hybridized electron-hole states called “chiral Andreev edge states” propagate along this interface in the direction determined by the magnetic field.

Continue reading… Harold Baranger (Duke University)

Link to video

Electrons in 2D moiré superlattices

 
When two van der Waals materials of slightly different orientations or lattice constants are overlaid, a moiré pattern emerges. The moiré pattern introduces a new length scale, many times the lattice constant of the original materials, for Bragg scattering of Bloch electrons in each layer.  This gives rise to moiré minibands and rich emergent phenomena. In this talk I will discuss recent experiments on angle-aligned semiconductor heterobilayers, which exhibit remarkable correlated insulating states. I will also discuss the prospect of using moiré superlattices as a Hubbard model quantum simulator.  

Continue reading… Jie Shan (Cornell)

New Forces: Dark Matter, Electric Dipole Moments and the Baryon Asymmetry of the Universe 

Abstract: I will discuss minimal gauge extensions of the Standard Model where a new sector is predicted from the cancellation of gauge anomalies. As part of this new sector, there is a dark matter candidate and new sources of CP violation. I will discuss the dark matter phenomenology and the prediction of large electric dipole moments (EDMs) for the electron and the neutron. I will also discuss how to address the baryon asymmetry of the Universe.

Host: Pavel Fileviez Perez

Continue reading… Alexis Plascencia (CWRU)

Title:

Non-equilibrium phenomena of ultracold quantum gasses trapped in optical lattice potentials.

Charles Brown, Department of Physics, University of California, Berkeley

Youtube video

Abstract:

Experiments with quantum gasses trapped in optical lattices, an analog of particles in a solid crystalline lattice, shed light on the behavior of condensed-matter systems, including solid-state materials.  Studying non-equilibrium phenomena of quantum gasses in optical lattices provides a method to explore how a lattice’s energy band structure is augmented by inter-particle interactions (band renormalization). Separately, studying such phenomena provides a method to explore the geometric and topological structure of a lattice’s energy bands.

Continue reading… Charles Brown (University of California, Berkeley)

Link to video

Cellular mechanobiology: from screening to disease biophysics

Cells are materials and the physical properties of cells are critical for many physiological functions including how cells deform to circulate through the body and how cells resist mechanical stresses.  A major goal of the Rowat lab is to understand how cells maintain their physical properties and regulate them in response to external cues. To achieve this goal, we developed a high throughput platform to quantify cell deformability using knowledge of the physics of fluid flow through porous media. We recently conducted a screen of 1280 small molecules and discovered compounds that make cancer cells stiffer and less invasive. 

Continue reading… Amy Rowat (UCLA Integrative Biology)

Special time 12:30 pm ET!!

The Neutron Decay Anomaly: how it may be a window to new Physics

In this talk I will first review a long-standing discrepancy between the neutron lifetime as measured in beam and in bottle experiments. If this discrepancy is not due to a systematic error, it may be due to novel mechanisms for neutron transmutation into new, as yet unknown elementary particles. These particles would be electrically neutral, or so-called “dark”. We will explain several scenarios for the possibility of neutron transmutation into dark particles. For example,

Continue reading… Benjamin Grinstein (UCSD)

Title: Thermal transport in clean semimetals – an application of electron hydrodynamics

Alessandro Principi, Department of Physics & Astronomy, University of Manchester

Youtube video

Abstract:

It is well known that clean compensated semimetals, e.g. two-dimensional monolayer and bilayer graphene near the charge neutrality point, can exhibit a greatly enhanced Lorenz ratio between the electronic thermal conductivity and the electric conductivity. In contrast to this, three-dimensional compensated semimetals such as WP2 and Sb with indirect negative gap typically exhibit a reduced Lorenz ratio. We propose that the reason for this puzzling difference lies in the ability of indirect-gap semimetals to sustain sizable regions of electron-hole accumulation near the contacts,

Continue reading… Alessandro Principi (University of Manchester)

Link to video

Interpretable Machine Learning of Quantum Emergence

Decades of efforts in improving computing power and experimental instrumentation were driven by our desire to better understand the complex problem of quantum emergence. However, the increasing volume and variety of data made available to us today present new challenges. I will discuss how these challenges can be embraced and turned into opportunities by employing machine learning. The rigorous framework for scientific understanding physicists enjoy through our celebrated tradition requires the interpretability of any machine learning essential. I will discuss our recent results using machine learning approaches designed to be interpretable from the outset.

Continue reading… Eun-Ah Kim (Cornell)

Photon Emission from Circular Equatorial Orbiters around Kerr Black Holes

We consider monochromatic and isotropic photon emission from circular equatorial Kerr orbiters. We calculate the critical curve delineating the region of photon escape from that of photon capture in each emitter’s sky, allowing us to derive analytic expressions for the photon escape probability and the redshift-dependent total flux collected on the celestial sphere as a function of emission radius and black hole parameters. This critical curve generalizes to finite orbital radius the usual Kerr critical curve and displays interesting features in the limit of high spin.

Continue reading… Delilah Gates (Harvard)

Global density wave formation in graphene via local symmetry breaking

 
Christopher Gutierrez, Department of Physics & Astronomy, UCLA

Abstract.– Two-dimensional materials offer a robust platform for investigating emergent behavior owing to the high tunability of their electronic properties. For instance, the ability to design electronic band structures through moiré superlattices in twisted graphene multilayers has led to the discovery of several symmetry-broken and topological phases. However, such twisted structures require exquisite care in their assembly and have micrometer dimensions that make spectroscopic measurements challenging.

In this talk, I will describe an alternative method to induce a symmetry-broken phase in graphene at the millimeter scale.

Continue reading… Christopher Gutierrez (UCLA)

Link to video

Quantum Magic in Moiré Lattices

 
The remarkable properties of electrons moving through crystalline lattices, which brought us the semiconductor electronics revolution, continue to surprise us. Recently, electrons in artificial Moiré lattices have emerged as an extraordinary new platform. The simplest such moire material consists of a pair of graphene sheets twisted relative to one another. At a  “magic” angle of about 1 degree, a variety of phenomena, including strong-coupling superconductivity, is observed. In this talk, I will review this rapidly moving field and describe our theoretical ideas that invoke the geometry of quantum states and topological textures like skyrmions.

Continue reading… Ashvin Vishwanath (Harvard University)

On 1D, N = 4 Supersymmetric Sachdev-Ye-Kitaev (SYK) Models

Proposals are made to describe 1D, N = 4 supersymmetrical systems that extend S-Y-K models by compactifying from 4D, N = 1 supersymmetric Lagrangians involving chiral, vector, and tensor supermultiplets. The coupling constants in the superfield Lagrangians are arbitrary, and can be chosen to be Gaussian random. In that case, these 1D, N = 4 supersymmetric S-Y-K models would exhibit Wishart-Laguerre randomness, which share the same feature among 1D, N = 1 and N = 2 models in literature. One difference though, is our models contain dynamical bosons.

Continue reading… Hazel Mak (Brown University)

Topological phase transitions of p-orbitals (Group-V) in 2D honeycomb lattices

 
Santosh Kumar, Department of Physics, Case Western Reserve University; University of Toronto
 
Youtube video

Topological materials, which hold promise for a wide range of technological applications due to their exotic electronic properties, have attracted a great deal of theoretical and experimental interest over the past decade, culminating in the 2016 Nobel Prize in physics. In this talk, I will explore the universal topological properties of p-orbitals placed in 2 dimensional D6h symmetry which is realized in real materials made of 2D group V-elements (Sb,

Continue reading… Santosh Kumar

No classes or seminars

Continue reading… No Seminar

Continue reading… No seminar (March Meeting)

An Early Period of QCD Confinement for Fun and Profit

Abstract: I’ll discuss the possibility that QCD, the SU(3) encapsulating the strong nuclear force in the Standard Model, undergoes a period in the early history of the Universe in which it confines with a much larger confinement scale than is observed today. I’ll talk about the mechanics of how one can realize such a phenomenon, what the Universe would look like during this period and phenomenological implications, and potential applications to realize the observed baryon asymmetry or a modified picture for dark matter freeze out.

For information about the speaker see this link

Host: Pavel Fileviez Perez

Continue reading… Tim Tait (UC Irvine)

Viscous fluids of electrons

Department of Physics, University of Colorado Boulder

Youtube video

Abstract.– It was conjectured over 50 years ago that electrons in high-quality conductor could flow collectively as a viscous fluid, just like air or water.  While impurities and Umklapp scattering forbid this behavior in conventional metals, it has now become possible to study electrons that flow like classical fluids in high-quality devices.  I will overview the nature of hydrodynamic transport in electrons together with some recent experiments that allow us to directly probe this behavior.

Continue reading… Andrew Lucas (University of Colorado Boulder)

Link to video

El Niño as a Topological Insulator: A Surprising Connection Between Climate, and Quantum, Physics

Symmetries and topology play central roles in our understanding of physics. Topology, for instance, explains the precise quantization of the Hall effect and the protection of surface states in topological insulators against scattering from disorder or bumps. However discrete symmetries and topology have up until now played little role in our thinking about the fluid dynamics of oceans and atmospheres. In this talk I show that, as a consequence of the rotation of the Earth that breaks time reversal symmetry,

Continue reading… Brad Marston (Brown University)

A Classical, Non-Singular Bounce

Bouncing cosmological models offer a viable alternative to Big-Bang cosmology and have gained recent attention. In a bouncing cosmology, the universe is initially contracting towards a minimum size before expanding. Such cosmological models are geodesically complete by construction and offer simple solutions to problems such as the Horizon problem. I will present a model that realizes such a cosmology and discuss its analytical and numerical properties. I will also discuss ongoing work on the stability of cosmological perturbations and possible future directions.

Host: Glenn Starkman

Zoom meeting ID:  999 3023 4812
For the password to access the meeting please contact one of us:
Kurt Hinterbichler: kjh92
Kara Farnsworth: kmf137
Ellen Rabe: exr223
Idit Zehavi: ixz6
at case.edu

Continue reading… Ozenc Gungor (CWRU)

Exciting dynamics in multiple time dimensions

Ivar Martin, Materials Science Division, Argonne National Laboratory

Youtube video

Abstract. — Externally driving a dynamical system, be it quantum or classical, effectively increases the number of its time dimensions.  In this talk, I will describe how the extra time dimensions can be harnessed to synthesize topological insulators purely in the time domain, describe their possible applications for energy conversion and quantum engineering, and point out connections to localization and chaos.

Host: Shulei Zhang

Continue reading… Ivar Martin (Argonne National Laboratory)

Line Intensity Mapping at millimeter wavelengths with on-chip spectrometers

Recent advances in superconducting technology have enabled dramatic improvements in the sensitivity of millimeter and sub-millimeter wavelength instruments in the last decade and helped to usher in the era of precision cosmology. The next frontier is intensity mapping: using large arrays of spectrometers to build a 3D model of the emission from galaxies, with the ability to measure the star formation history throughout the epoch of reionization and to significantly constrain extensions to contemporary cosmology and inflation. The key to this technology are superconducting detectors and the microwave readout required to populate dense focal planes.

Continue reading… Erik Shirokoff (UChicago)

Modulating magnon transport in ferromagnetic and antiferromagnetic materials

Luqiao Liu, Electrical Engineering and Computer Science, MIT

Youtube video

Abstract.– Spin waves are considered as one of the promising candidates for realizing unconventional computing and information processing. Compared with other forms of waves, spin wave has the advantage of short wavelength, intrinsic nonlinearity, and non-reciprocity. In this talk, I will discuss some of our experimental efforts on developing magnonic structures for these purposes. In the first effort, we demonstrated mutual interactions between magnons and magnetic domain walls in a ferromagnetic thin film,

Continue reading… Luqiao Liu (MIT)

Link to video

Old and recent puzzles in flavour physics

Abstract: The origin of the hierarchical spectrum of quark and lepton masses observed in Nature is one of the long-standing open questions in particle physics. The recent hints of non-standard phenomena in low-energy flavour-changing processes have opened new directions in model building which might address this issue, and possibly connect it to the more general search for physics beyond the Standard Model. In this talk I will critically review these hints and highlight some of the new research directions they might suggest.

Continue reading… Gino Isidori (University of Zurich)

Stable, ghost-free solutions in UV non-local gravity

I consider higher derivative, UV modifications to GR. In particular, I will focus on a specific kind of string theory-inspired higher derivative gravity where one includes derivatives to all orders in the action. First, I will discuss how such a non-local theory of gravity admits stable, non-singular bouncing solutions in the absence of matter. Moreover, around this bouncing background, there exists only one propagating (and ghost-free) scalar mode, and no vector or tensor modes. Next, I will discuss the general analysis of scalar-vector-tensor perturbations in non-local gravity – in particular,

Continue reading… Shubham Maheshwari (Groningen)

First-principles calculations of polarons in real materials

Carla Verdi, Faculty of Physics, University of Vienna

Zoom recording

Abstract. — Polarons are quasiparticles formed by electrons ‘dressed’ by a phonon cloud and represent a paradigmatic example of an emergent state in condensed matter. The presence of polarons can strongly influence the fundamental characteristics and functionalities of the host materials. Despite the broad scientific and technological interest in polarons, their properties are poorly understood. In this talk, I will present our recent work aimed at describing polarons from first principles in real materials.

Continue reading… Carla Verdi (University of Vienna)

Link to video

Co-sponsored by the Program in Cell Biology and Department of Physics at CWRU

Kurt Hinterbichler (Physics) on the Nobel Prize in Physics; Ron Conlon (Department of Genetics and Genome Sciences) on the Prize in Chemistry; and Donald Anthony (Department of Medicine) on the Prize in Physiology or Medicine. 

The 2020 Nobel Prize in Physics was awarded half to Roger Penrose “for the discovery that black hole formation is a robust prediction of the general theory of relativity,” and half to Reinhard Genzel and Andrea Ghez “for the discovery of a supermassive compact object at the centre of our galaxy.” 

Continue reading… The 2020 Nobel Prizes in Science

The Cosmological Phonon: Symmetries on Sub-Horizon Scales

Curvature perturbations during inflation, which seed anisotropies in the CMB, can be described as phonons propagating on the inflationary background. Indeed the spacetime expansion breaks spontaneously time diffeomorphisms and Lorentz boost invariance generating such phonon-like behaviour. This representation is at the heart of the construction of the Effective Field Theory (EFT) of inflation. In this talk I will present an algebraic classification of the possible symmetries of a shift-symmetric scalar that is assumed to non-linearly realise Lorentz boosts. Such theories include for instance scalar modes in the EFT of inflation on sub-horizon scales,

Continue reading… Tanguy Grall (Cambridge)

Field theories of micromagnetism in XY ferromagnet and antiferromagnet

Sayak Dasgupta

Stewart Blusson Quantum Matter Institute, University of British Columbia

Youtube video

Abstract. — Micromagnetic field theories effectively capture the long-range static structures and dynamics of ordered spin systems at temperatures below their ordering temperatures. The field theory, if expressed in the correct form, further elucidates hidden features in the order. We discuss two such instances. First, we take a look at the 2+1D XY ferromagnet whose continuum field theory has been extensively studied in the context of the Kosterlitz-Thouless phase transition [1].

Continue reading… Sayak Dasgupta (University of British Columbia)

Link to video

Zoom ID:  943 5186 3408, Passcode:  627107

https://cwru.zoom.us/j/94351863408

Theory of quantum anomalous Hall and axion insulators

Topological insulators are insulating crystals in which the electronic wave functions are topologically twisted in a certain sense. In recent years, a bewildering variety of types of topological insulators have been proposed. In this talk I will focus on two. First, I will introduce 2D quantum anomalous Hall insulators, which exhibit a quantum Hall effect without any external electric field. I will briefly discuss some computational efforts to identify new,

Continue reading… David Vanderbilt (Rutgers University)

Spreading Dynamics of Water Droplets on a Completely Wetting Surface

Mesfin Tsige

School of Polymer Science and Polymer Engineering, The University of Akron

Youtube video

Abstract. — There is a tremendous need for a greater understanding of the properties of matter at surfaces and interfaces at the nanometer scale mainly driven by the unprecedented impact of nanoscale materials in current industrial products. It is well known that matter behaves in complex ways and exhibits exotic properties at nanometer length scales.  However, understanding the behavior of matter at such length scales using experimental methods has in general been very difficult.

Continue reading… Mesfin Tsige (University of Akron)

Reconstructing cell phenotypic transition dynamics from single cell data

Recent advances in single-cell techniques catalyze an emerging field of studying how cells convert from one phenotype to another, i.e., cell phenotypic transitions (CPTs). Two grand technical challenges, however, impede further development of the field. Fixed cell-based approaches can provide snapshots of high-dimensional expression profiles but have fundamental limits on revealing temporal information, and fluorescence-based live cell imaging approaches provide temporal information but are technically challenging for multiplex long- term imaging. My lab is tackling these grand challenges from two directions, with the ultimate goal of integrating the two directions to reconstruct the spatial-temporal dynamics of CPTs.

Continue reading… Jianhua Xing (University of Pittsburgh)

Continue reading… No seminar (Thanksgiving holiday)

Link to video

Reducing Nuclear Weapons and the Risk of Nuclear War

The Cold War ended 30 years, but nuclear weapons and the threat of nuclear war are still with us. Nine countries together deploy about 10,000 nuclear weapons, most with a destructive potential an order of magnitude greater than the bomb that destroyed Hiroshima. The United States and Russia, which together account for 90 percent of global stockpiles, each maintain about 1000 nuclear weapons on constant alert, ready to be launched in a few minutes. Arms control agreements that have constrained US and Russian arsenals and provided stability are on the brink of collapse,

Continue reading… Steve Fetter (School of Public Policy, University of Maryland)

Precision Standard-Model Prediction of epsilon_K

The parameter epsilon_K describes CP violation in the neutral kaon
system and is one of the most sensitive probes of new physics. The large
uncertainties related to the charm-quark contribution to epsilon_K have
so far prevented a reliable standard-model prediction. In this talk, I
will review mixing in the neutral kaon system, and then show that CKM
unitarity suggests a unique form of the weak effective Hamiltonian in
which the short-distance theory uncertainty of the imaginary part is
dramatically reduced. The uncertainty related to the charm-quark
contribution is now at the percent level.

Continue reading… Joachim Brod (University of Cincinnati)

Creating and probing new phases in quantum materials

Qiong Ma

Physics Department, Massachusetts Institute of Technology

Physics Department, Boston College

Abstract: There are two fundamental ways for us to understand nature. One way is to understand our world by breaking it into smaller and smaller building blocks. Primary examples include the discoveries of chemical elements and elementary particles. The other way is: given the same building blocks, we ask what the possible ways are for them to be organized by nature. On the level of condensed matter, even with the same chemical composition and parent lattice structure,

Continue reading… Qiong Ma (MIT)

Link to video

From cat skin to submarines – new materials that are a bit of a stretch.

Liquid crystals are self-organising fluids that are perhaps best known for their use in displays (LCDs) and much of the research in the area over the past 30 years or so has been focused on achieving faster switching and more complex images in flat panel TVs. However, such technology is now mature and for some time now new, exciting properties of liquid crystals that might lead to rather futuristic applications have been emerging.  

Continue reading… Helen Gleeson (University of Leeds)

On the quest of finding the surface of articular cartilage

The primary role of articular cartilage (AC) is to provide a smooth lubricated surface between contacting and moving bones, which allows for ultralow friction as well as wear protection to the sliding epiphysis for almost a century in healthy people. The physical and chemical nature of the topmost surface of AC has intrigued researchers since it was first reported in 1951, called the “lamina splendens”. This layer has been the source of heated and controversial scientific debate since it was first reported. The lamina splendens is important because it forms the interfaces between the cartilage and synovial fluid,

Continue reading… Roberto Carlos Andresen Eguiluz (UC Merced)

The Newman-Penrose Map and the Classical Double Copy

Abstract: Double copy relations between gauge and gravitational theories, originally found in the context of string theory and scattering amplitudes, have recently been realized in a classical setting as maps between exact solutions of gauge theories and gravity. I will present a new map between a certain class of real, exact solutions of Einstein’s equations and self-dual solutions of the flat-space vacuum Maxwell equations. This map, which we call the Newman-Penrose map, is well-defined even for non-vacuum, non-stationary spacetimes, providing a systematic framework for exploring gravity solutions in the context of the double copy that have not been previously studied in this setting.

Continue reading… Kara Farnsworth (CWRU)

Current Fluctuations Driven by Magnetic Resonance

Arne Brataas

Department of Physics, Norwegian University of Science and Technology

When spins in magnetic materials precess, they emit currents into the surrounding conductors. We will explain how dynamical magnets also induce current noise. The shot noise characterizes and detects magnetic resonance and new aspects of electron transport in magnetic nanostructures.

We generalize the description of current fluctuations driven by spin dynamics in three ways using scattering theory. First, our approach describes a general junction with any given electron scattering properties. Second, we consider antiferromagnets as well as ferromagnets.

Continue reading… Arne Brataas (NUST, Norway)

Link to video

Traveling Waves in Brains

What we know about brain function has tracked technology.  The discovery of weak electrical signals from the surface of the scalp by Hans Berger in 1924 hinted at complex oscillatory activity.  Recordings from single neurons in the cerebral cortex by David Hubel and Torsten Wiesel in 1960 made possible by the tungsten microelectrode showed that each neuron in the visual cortex responds selectively to
visual stimuli.  The development of microelectrode arrays in the 21st century has revealed a mesoscopic
surprise:  The oscillations in the cortex are not synchronous,

Continue reading… Terry Sejnowski (Salk Institute)

Energy as a guiding principle in nonlinear structure formation

Abstract: One goal of studies of large scale structure formation is to understand why the dense, virialized clumps which host galaxies form where they do.  In cold dark matter cosmologies, the late time field retains some memory of the initial conditions, which models of dark matter halo formation try to exploit.  The simplest models are motivated by a spherical collapse calculation which dates back to the early  1970s.  In the late 1980s, this approximation for the physics of collapse was coupled with the heuristic assumption that collapse occurs around regions that are maxima of the initial matter density fluctuation field. 

Continue reading… Ravi Sheth (University of Pennsylvania)

Spintronics: Fundamentals and recent developments

Sergio M. Rezende

Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil

Zoom Recording

Abstract.— Spintronics is the field of physics and technology that makes use of the electron spin to transport and process information. The birth of this field dates to the 1980s and was triggered by the discovery of the Giant Magnetoresistance in magnetic multilayers. In the 2000s this field gained new impulse with the discovery of several phenomena involving spin currents and ferromagnetic films, such as the spin Hall effect,

Continue reading… Sergio M. Rezende (Universidade Federal de Pernambuco, Brazil)

Light Does Not Always Travel On The Light Cone

Despite the massless character of their associated particles, electromagnetic and gravitational radiation do not travel strictly on the null cone in curved spacetimes. This ‘tail’ phenomenon was first uncovered by the mathematician Jacques Hadamard in his study of partial differential equations; and introduced to physicists by Robert Brehme and Bryce DeWitt — they pointed out that there is a novel self-force on electromagnetically charged systems arising from this inside-the-light-cone signal. The gravitational counterpart of this self-force (derived by Mino, Misao Sasaki, Tanaka; and also by Quinn and Wald) is of relevance to understanding gravitational waves generated by compact bodies orbiting near supermassive black holes,

Continue reading… Yi-Zen Chu (National Central University, Taiwan)

Seeing the dark: gravitational relics of dark photon production

Axion-like particles are a recurrent feature of models of early Universe phenomena, spanning inflation, dark matter, and solutions to the Hubble tension. The nonperturbative decay of axions into beyond the Standard Model photons is a generic feature of these models. I will present the complex nonperturbative and nonlinear dynamics of axion–gauge-field couplings, studied via numerical simulation. These scenarios result in a significant stochastic background of gravitational waves, which provides various means to rule out and constrain models. In the two examples I will present, the (over)production of GHz gravitational waves at preheating imposes the tightest constraints on the inflaton’s axial coupling to gauge fields,

Continue reading… Zach Weiner (University of Illinois)

Which geometries can and which cannot be given to thin nematic elastomer surfaces

Hillel Aharoni

Department of Physics, Weizmann Institute of Science

Youtube video

Abstract.– Thin nematic elastomer sheets can be programmed, via the nematic director field embedded into them, to take different shapes in different environments. Recent experiments from various groups demonstrate excellent control over the director field, thus opening a door for achieving accurate and versatile designs of shape-shifting surfaces. At the crux of any effort to implement this design mechanism lies the inverse design problem —

Continue reading… Hillel Aharoni (Weizmann Institute of Science, Israel)

Link to video

Electronic Transport in Strain-Engineered Graphene 

There is wide interest in using strain-engineering to modify the physical properties of 2D materials, for both basic science and applications. Deformations of graphene, for example, can lead to the opening of band gaps, as well as the generation of pseudo-magnetic fields and novel electronic states. We demonstrate how controllable, device-compatible strain patterns in graphene can be engineered by depositing graphene on corrugated substrates. We discuss several techniques for creating corrugated substrates, focusing on periodic spherical curvature patterns in the form of closely packed nanospheres.

Continue reading… Nadya Mason (University of Illinois, Urbana-Champaign)

Decoding Chemical Evolution and Nucleosynthesis

I will discuss insights from analytic and numerical models of galactic chemical evolution and observations of Milky Way elemental abundances from the Sloan Digital Sky Survey’s APOGEE project. Under generic model assumptions, abundances and abundance ratios approach an equilibrium in which element production from nucleosynthesis is balanced by element depletion from star formation and outflows. The efficiency of outflows required to reproduce observed abundances is strongly degenerate with the uncertain overall scale of supernova yields. APOGEE observations show that the distributions of stars in (magnesium,iron,age)-space change steadily across the Milky Way disk,

Continue reading… David Weinberg (Ohio State University and Institute for Advanced Study)

Optics of materials with Dirac and Weyl fermions

Alexey Belyanin

Department of Physics and Astronomy, Texas A&M University

Youtube video

Relativistic Dirac and Weyl fermions were extensively studied in quantum field theory. Recently they emerged in the non-relativistic condensed-matter setting as gapless quasiparticle states in some types of crystals. Notable examples of 2D systems include graphene and surface states in topological insulators such as Bi2Se3. Their 3D implementation is Dirac and Weyl semimetals. Most of the research has been focused on their topological properties and electron transport. However,

Continue reading… Alexey Belyanin (Texas A&M University)

Link to video

Modeling Mechanical Actuation in Liquid Crystal Polymers

Liquid crystal polymer networks undergo reversible shape change in response to any stimulus that affects their nematic order, allowing them to flex like artificial muscles. These soft actuators can be fabricated as thin films, surface coatings, or 4D printed solids and have potential applications in soft robotics, biomedical devices, microfluidics, and sensors. Trajectories for shape change are “programmed” by patterning the nematic director when the polymer is cross-linked. Actuation is induced when the strength of nematic order is modulated by stimuli such as a change of temperature,

Continue reading… Robin Selinger (Advanced Materials and Liquid Crystal Institute, Kent State Univ)

Title:  Protein dynamics: Connecting in vitro, in cell, and in vivo

Although biomolecules evolved to function in the cell, most biochemical and biophysical studies have been carried out in vitro. A combination of in vitro, in-cell, and in vivo studies will highlight how steric and non-steric interactions modulate protein folding and protein-RNA interactions. I will introduce a customized pipeline that combines meganuclease mediated transformation with fluorescence-detected temperature-jump microscopy to image fast dynamics of biomolecules in living zebrafish with single-cell resolution. To interpret in vivo and in-cell results, an in vitro systematic series of solvation environments will distinguish contributions from non-steric and steric interactions to stability,

Continue reading… Caitlin Davis (Yale University)

Chameleon dark energy in the lab
 
The accelerated expansion of the universe hints at the existence of a new light degree of freedom in the gravitational sector.  Such a degree of freedom, generally taken to be a scalar, mediates a fifth force between matter particles.  This property is in tension with existing tests of gravity, unless the fifth force is screened, i.e. it dynamically weakens in certain environments.  A new generation of gravitational experiments, being performed in the laboratory, are designed to be sensitive to screened forces, and have made great headway towards detecting or ruling out screened forces over the past several years. 

Continue reading… Benjamin Elder (University of Hawaii)

Title: Harnessing Nitrogen Vacancy Centers in Diamond for Next-Generation Quantum Science and Technology

Chunhui Du, Department of Physics, University of California, San Diego

Zoom Recording

Abstract: Advanced quantum systems are integral to both scientific research and modern technology enabling a wide range of emerging applications. Nitrogen vacancy (NV) centers, optically-active atomic defects in diamond, are directly relevant in this context due to their single-spin sensitivity and functionality over a broad temperature range. Many of these advantages derive from their quantum-mechanical nature of NV centers that are endowed by excellent quantum coherence,

Continue reading… Chunhui Du (UC San Diego)

Link to video

The Information Paradox in the Age of Holographic Entanglement Entropy

The black hole information paradox — whether information escapes an evaporating black hole or not —  remains one of the greatest unsolved mysteries of theoretical physics. The apparent conflict between validity of semiclassical gravity at low energies and unitarity of quantum mechanics has long been expected to find its resolution in the deep quantum gravity regime. Recent developments in the holographic dictionary and in particular its application to entanglement, however, have shown that a semiclassical analysis of gravitational physics has a hallmark feature of unitary evolution.

Continue reading… Netta Engelhardt (MIT)

Is GR unique?

Not sure. I will present an iterative Hamiltonian approach, to build up a gravity theory with all constraints being first class and thus possesses only 2 local degrees of freedom. The results are conjectural, rather than conclusive. If it is true, however, it implies GR may not be unique in the 4-dimensional space-time. If time permits, I will also briefly discuss the recently proposed 4D Einstein-Gauss-Bonnet gravity, which was another attempt of mine, yet probably unsuccessful one, along the line.

Zoom meeting ID:  999 3023 4812
For the password to access the meeting please contact one of us:
Kurt Hinterbichler: kjh92
Alexis Plascencia: adp110
Ellen Rabe: exr223
Idit Zehavi: ixz6
at case.edu

Continue reading… Chunshan Lin (Warsaw)

Quantum detailed balance & exact solutions of interacting driven-dissipative systems

Aashish Clerk, Pritzker School of Molecular Engineering, The University of Chicago

Zoom Recording

I’ll discuss a new approach that allows one to non-perturbatively find the steady states of driven-dissipative systems described by a Lindblad master equation.  The focus will be on driven nonlinear resonator systems, a class of system that is at the forefront of research in superconducting quantum circuits and quantum optics.    I’ll discuss new phenomena revealed by these solutions, including a new kind of generalized photon blockade effect that is effective even for extremely weak system nonlinearity,

Continue reading… Aashish Clerk (U Chicago)

Link to video

Data Science in Art: Discerning the Painter’s Hand

Ken Singer, Ambrose Swasey Professor of Physics

with

Michael Hinczewski, Warren E. Rupp Associate Professor of Physics

Ina Martin, Senior Research Associate (Physics), Adjunct Faculty in the Department of Materials Science and Engineering

Betsy Bolman, Elsie B. Smith Professor in the Liberal Arts and Chair, Department of Art History and Art 

The Departments of Art History and Art, Physics, Materials Science and Engineering,

Continue reading… Ken Singer et al (CWRU Physics and Art History)

A CMB Millikan Experiment with Cosmic Axiverse Strings

We study axion strings of hyperlight axions coupled to photons. These axions strings produce a distinct quantized polarization rotation of CMB photons which is O(1%).  As the CMB light passes many strings, this polarization rotation converts E-modes to B-modes and adds up like a random walk. Using numerical simulations we show that the expected size of the final result is well within the reach of current and future CMB experiments through the measurement of correlations of CMB B-modes with E- and T-modes. The quantized polarization rotation angle is topological in nature and its value depends only on the anomaly coefficient,

Continue reading… Anson Hook (Maryland)

Topology in Charge-Density Wave Systems

Barry Bradlyn

Physics department, the University of Illinois at Urbana-Champaign

Zoom recording

Abstract.-The recent discover of Weyl semimetals has shown that topological effects can play a significant role in the behavior of gapless systems. However, correlation effects in known Weyl semimetals did not seem to play a significant role in most materials. Here I will show that the charge density wave compound (TaSe_2)_4I is a Weyl semimetal with strong correlations due to electron-phonon coupling. I will show how the topological charge of the Weyl nodes leaves its mark on the behavior of the collective phase mode of the charge density wave,

Continue reading… Barry Bradlyn (UIUC)

Link to video

Challenging the Standard Model With High-Energy Neutrinos

Particle physicists are living in interesting times. We are faced with the paradox of a highly predictive theory –the Standard Model — that is filled with patterns that are hard to explain. We are also faced with “known unknowns,” like dark matter. Right now, neutrinos are the only particles exhibiting beyond Standard Model behavior, seen in the flavor transitions called neutrino oscillations, which are due to neutrino mass. This is an important clue towards a larger theory. Building on this, I am interested in what other types of flavor transitions neutrinos may have due to new particles,

Continue reading… Carlos Arguelles Delgado (Harvard University)

Halo and galaxy assembly bias

Measuring galaxy clustering is an effective way to gain knowledge of galaxy formation and constraining cosmology. Cosmology determines dark matter halo population and clustering, and halo clustering and halo occupation determine the galaxy clustering. It is important to understand halo clustering and galaxy-halo connection to build halo occupation models. In N-body simulations, halo clustering is shown to depend not only on halo mass but also on secondary halo properties, which is called the halo assembly bias. However, traditional halo occupation models only consider halo mass dependence and ignore effects caused by secondary halo properties.

Continue reading… Xiaoju Xu (CWRU)

Tunable correlated and topological states in twisted graphene heterostructures

Matthew Yankowitz

Department of Physics, University of Washington

Zoom Recording

Abstract.– In van der Waals heterostructures composed of two rotated graphene sheets, a moiré superlattice results in the emergence of flat electronic bands over a small range of twist angles. A variety of highly tunable correlated and topological states have recently been identified in these platforms owing to the quenched kinetic energy of charge carriers and the intrinsic Berry curvature of the flat bands. I will discuss our recent work investigating these states in three different twisted graphene platforms.

Continue reading… Matthew Yankowitz (University of Washington)

Link to video

Topological Quasiparticles: Magnetic Skyrmions

The field of spintronics, or magnetic electronics, is maturing and giving rise to new subfields [1].  An important ingredient to the vitality of magnetism research in general is the large complexity due to competitions between interactions crossing many lengthscales and the interplay of magnetic degrees of freedom with charge (electric currents), phonon (heat), and photons (light) [2].  One perfect example, of the surprising new concepts being generated in magnetism research is the recent discovery of magnetic skyrmions.  Magnetic skyrmions are topologically distinct spin textures that are stabilized by the interplay between applied magnetic fields,

Continue reading… Axel Hoffmann (University of Illinois, Urbana-Champaign)

A Dark Matter Interpretation of Excesses in Multiple Direct Detection Experiments

We present a novel unifying interpretation of excess event rates observed in several dark matter direct-detection experiments that utilize single-electron threshold semiconductor detectors. Despite their different locations, exposures, readout techniques, detector composition, and operating depths, these experiments all observe statistically significant excess event rates of ~10 Hz/kg. However, none of these persistent excesses has yet been reported as a dark matter signal because their common spectral shapes are inconsistent with dark matter particles scattering elastically off detector nuclei or electrons. We show that these results can be reconciled if the semiconductor detectors are seeing a collective inelastic process known as a plasmon.

Continue reading… Gordan Krnjaic (Fermilab)

Continue reading… No seminar (faculty meeting)

Link to video
 

Decoding Primordial Fluctuations
 
All the information we will ever obtain from the primordial universe is imprinted in the spatial correlations of fluctuations at the hot Big Bang. I will explain how an influx of ideas from various areas of fundamental physics is providing us with new conceptual and practical tools to decode the physics of these primordial fluctuations. A thorough understanding of the fluctuations will give us insight into particle physics at the highest energies and may provide a window into the nature of spacetime itself.

Continue reading… Guilherme Pimentel (Amsterdam, Leiden)

Ultralight Fermionic Dark Matter

Tremaine and Gunn argued long ago that fermionic dark matter lighter than a few hundred eV is not feasible, based on the Pauli exclusion principle. We highlight a simple way of evading this conclusion which can lead to various interesting consequences. In this scenario, a large number of fermionic species with quasi-degenerate masses and no couplings, other than gravitational, to the standard model are assumed. Nonetheless, we find that gravitational interactions can lead to constraints on the relevant parameter space, based on high energy data from the LHC and cosmic ray experiments,

Continue reading… Hooman Davoudiasl (Brookhaven)

Charge-spin conversion effects and magnetization switching enabled by spin-orbit coupling

Pietro Gambardella

Department of Materials, ETH Zurich, CH – 8093 Zürich, Switzerland

Zoom Recording

The coupling of spin and orbital angular momenta underlies the magnetoelectric properties of matter. Although small, the spin-orbit interaction determines the preferred orientation of the order parameter in ferromagnets and antiferromagnets as well as the possibility to excite the magnetization out of equilibrium while ensuring the conservation of angular momentum. In recent years, advances in the understanding of the nonequilibrium charge-spin conversion processes mediated by the spin-orbit interaction have opened new perspectives for controlling the static and dynamic magnetization of all classes of magnetic materials,

Continue reading… Pietro Gambardella (ETH Zürich, Switzerland)

Radiating Macroscopic Dark Matter

Dark matter is believed to constitute about 5/6th of the matter in the universe, but its nature and interactions remain one of the great puzzles of fundamental physics. Despite extensive experimental efforts, there have been no widely believed detections of WIMPS, axions or any other physics Beyond the Standard Model (BSM) (except for neutrino oscillations, which are BSM principally by historical accident). The question then arises: could the Standard Model, the most accurate and extremely well-tested theory of all observed particles in nature, explain dark matter as well? Many models of exotic quark matter have been proposed,

Continue reading… Saurabh Kumar (CWRU)

Coherent information processing with on-chip microwave magnonics

Zoom Recording

In the race of post-CMOS computing technologies, coherent information processing with microwave circuits have demonstrated great potentials with the recent breakthrough in quantum computing, where both the quanta and the phase of the excitation states can be utilized for carrying and processing information. In this seminar, I will show that magnons—the collective excitations of exchange-coupled spins in magnetic materials—act as a new candidate for coherent information transfer and processing. Compared with other excitations, magnons exhibit special advantages: 1) their frequencies are naturally in the microwave regime and can be noninvasively tuned by an external magnetic field,

Continue reading… Yi Li (Argonne National Lab)

Continue reading… Jie Shan (Cornell)

TBA

Host: Harsh Mathur

Continue reading… Postponed: Aashish Clerk , University of Chicago

New Date to be determined

Continue reading… RESCHEDULED Axel Hoffmann (Univ Illinois, Urbana-Champaign)

TBA

Host: Lydia Kisley

Continue reading… Sveta Morozova, Department of Macromolecular Science and Engineering, Case Western Reserve University

Rescheduled for Fall 2020

Continue reading… RESCHEDULED Terry Sejnowski (Salk Institute)

Complex magnetic excitations in a honeycomb ferromagnet CrI3
Liuyan Zhao, Department of Physics, University of Michigan, Ann Arbor

Two-dimensional (2D) honeycomb ferromagnetic monolayers are predicted to host massless Dirac magnons because of the two equivalent magnetic sites per unit cell of the honeycomb lattice, mimicking Dirac electrons in graphene. More interestingly, the introduction of the next-nearest-neighbor Dzyaloshinskii-Moriya interaction breaks the sublattice equivalency and suggests the emergence of topological magnons in these honeycomb ferromagnets. Recenly, CrI3, a honeycomb ferromagnet, has attracked tremendous attention because of the long-range 2D ferromagnetic order in its monolayer, the interlayer antiferromagnetic order in its few layers,

Continue reading… CANCELLED until later notice: Prof. Liuyan Zhao, University of Michigan,Ann Arbor, Complex magnetic excitations in a honeycomb ferromagnet CrI3

New date to be determined

Data Science in Art: Discerning the Painter’s Hand

Ken Singer, Ambrose Swasey Professor of Physics

with

Michael Hinczewski, Assistant Professor of Physics

Ina Martin, Senior Research Associate (Physics), Adjunct Faculty in the Department of Materials Science and Engineering

Betsy Bolman, Elsie B. Smith Professor in the Liberal Arts and Chair, Department of Art History and Art 

The Departments of Art History and Art, Physics, Materials Science and Engineering, the Cleveland Museum of Art and the Cleveland Institute of Art have been collaborating to investigate the application of machine learning (ML) to artist attribution based on confocal optical profilometry data from student-produced painting via the brushstroke texture. 

Continue reading… RESCHEDULED Ken Singer et al (CWRU Physics and Art History)

New date to be determined

Modeling liquid crystal elastomers: from auto-origami to responsive surfaces and a light-powered soft robot

Liquid crystal elastomers combine the orientational order of liquid crystals with the elasticity of polymers. Remarkably, these materials flex and deform reversibly, driven by stimuli such as  illumination or heating, and can be programmed to morph from simple to complex shapes. The material’s liquid crystal director field, indicating the direction of molecular alignment, defines the local axis of induced contraction. We use GPU-based finite element elastodynamics modeling to study how patterns with director gradients and  topological defects give rise to complex actuation. 

Continue reading… RESCHEDULED Robin Selinger (Kent State)

Field theory of a hexagonal antiferromagnet with 3 sublattices

Sayak Dasgupta, John’s Hopkins University, Department of Physics

We present a classical field theory of magnetization dynamics in a generic 3-sublattice antiferromagnet in 2 spatial dimensions exemplified by the Heisenberg model on the triangular [1] and kagome [2] lattices. In a ground state, spins from the 3 sublattices are coplanar and at angles of 120° to one another such that S1+S2+S3=0. The six normal modes, shown in Fig. 1, either keep the spins in this plane (the a modes) or take them out of the plane (the b modes).

Continue reading… CANCELLED or postponed: Sayak Dasgupta, Johns Hopkins University, Field theory of a hexagonal antiferromagnet with 3 sublattices

Continue reading… Spring break, no seminar

Charge Constraints of Macroscopic Dark Matter

Macroscopic dark matter (macros) refers to a broad class of alternative candidates to particle dark matter with still unprobed regions of parameter space. Prior work on macros has considered elastic scattering to be the dominant energy transfer mechanism in deriving constraints on the abundance of macros for some range of masses and (geometric) cross-sections. However, macros with a significant amount of electric charge would, through Coulomb interactions, interact strongly enough to have produced observable signals on terrestrial, galactic and cosmological scales. We determine the expected phenomenological signals and constrain the corresponding regions of parameter space,

Continue reading… Jagjit Singh Sidhu (CWRU)

Continue reading… APS March meeting, no seminar

Continue reading… APS March Meeting, No seminar

Building a quantum computer using silicon quantum dots
 
The steady increase in computational power of information processors over the past half-century has led to smart phones and the internet, changing commerce and our social lives.  Up to now, the primary way that computational power has increased is that the electronic components have been made smaller and smaller, but within the next decade feature sizes are expected to reach the fundamental limits imposed by the size of atoms.  However, it is possible that further huge increases in computational power could be achieved by building quantum computers, which exploit in new ways of the laws of quantum mechanics that govern the physical world.  

Continue reading… Susan Coppersmith (Wisconsin/New South Wales)

Born-Infeld Theory Beyond the Leading Order

The modern approach to scattering amplitudes exploits the symmetries of effective field theories. In this talk, I will focus on Born-Infeld, a theory of non-linear electrodynamics that has a myriad of interesting properties: It can be obtained as the “double copy” of Yang-Mills and chiral perturbation theory and it is the supersymmetric truncation of low-energy brane dynamics. Born-Infeld theory also has a classical electromagnetic duality symmetry. I will discuss how one can use these nice properties to uniquely fix all tree-level amplitudes in the theory. At subleading order, I will address one-loop amplitudes and admissible higher derivative corrections to the Born-Infeld effective field theory.

Continue reading… Shruti Paranjape (University of Michigan)

List of speakers: not necessarily in that order, Please note earlier start at 12:30 pm and end at 2:00 pm

———————————-

Kyle Crowley, Electrical Transport in Chemically Exfoliated LixCoO2 in 2D Nanoflake Form

Brian Holler, 2D Semiconductor Transistors using Layered van der Waals Oxide MoO3 as High-K Gate Dielectric

Arvind Shankar Kumar, Negative Parabolic Magneto-resistance in a strongly interacting 2D Hole system in GaAs/AlGaAs

Mahdi Mehrnia, Fast, low-power defect-induced polarity switching of a magnetic vortex core

Ruihao Li, Nonlinear Planar Hall as Another Signature of Chiral Anomaly in Weyl Semimetals

Amol Ratnaparkhe,

Continue reading… CWRU Physics grad students, APS March meeting talks preview

Microwave amplification at the quantum limit: implementing and operating a Josephson parametric amplifier

A microwave electromagnetic field cooled down to millikelvin temperatures can reach its ground state: at this stage, all thermal fluctuations are suppressed and only quantum fluctuations remain. Reaching this regime enabled manipulation of the microwave fields at the single-photon level but also required the development of ultra-low-noise microwave amplifiers to ensure the detection of these quantum microwave states. Relying on non-dissipative parametric amplification using Josephson junctions, these Josephson parametric amplifiers (JPA) perform amplification while adding as little noise as allowed by quantum mechanics.

Continue reading… Audrey Bienfait (ENS-Lyon) Michelson Postdoctoral Prize Lecture

Interfacing quantum microwaves to spins and phonons

Circuit quantum electrodynamics is a currently very active field of research. Since the discoveries that an artificial spin, the so-called qubit, can be implemented using a superconducting non-linear circuit and can coherently interact with the electromagnetic field at the single-photon level, it has gathered strong interest for its potential for quantum computing but also for its ability to create, manipulate and detect microwave states with an exquisite precision. In this talk, I will present how the tools and concepts developed for quantum circuits can be used to interface microwaves and phonons,

Continue reading… Audrey Bienfait (ENS-Lyon) Michelson Postdoctoral Prize Colloquium

Magnetic resonance with quantum microwaves

In usual magnetic resonance experiments, the coupling between spins and their electromagnetic environment is quite weak, severely limiting the sensitivity of the measurements and any interaction at the quantum level between spins and microwaves. In this lecture, I will show that using a Josephson parametric microwave amplifier combined with high-quality factor superconducting micro-resonators cooled at millikelvin temperatures enable the implementation of a magnetic resonance spectrometer where the detection sensitivity is limited by quantum fluctuations of the electromagnetic field instead of thermal or technical noise. The small mode volume superconducting microwave resonator also enhances the spin-resonator coupling up to the point where quantum fluctuations have an effect on the spin dynamics: The spin spontaneous emission of microwave photons in the resonator is dramatically enhanced by the Purcell effect,

Continue reading… Audrey Bienfait (ENS-Lyon) Michelson Postdoctoral Prize Lecture

Phonon-mediated quantum state transfer and remote entanglement

Heavily used in classical signal processing, surface acoustic waves (SAWs) have also been proposed as a means to coherently couple distant solid-state quantum systems. Several groups have already reported the coherent coupling of standing SAWs modes to superconducting qubits, opening the door to the control and detection of quantum phonon states. In this lecture, I will explore the coherent coupling of superconducting qubits to propagating SAWs, demonstrating that quantum state transfer as well as remote entanglement generation between superconducting qubits using propagating SAWs can be realized.

Continue reading… Audrey Bienfait, (ENS-Lyon) Michelson Postdoctoral Prize Lecture

The Antikythera Mechanism: Discoveries Old & New

The Antikythera Mechanism, so named after the Greek island in whose waters it was salvaged in 1901 from a shipwreck datable to ca. 70-60 BCE, is a remarkable geared device that was constructed in the 2nd or 1st century BCE to calculate and display various astronomical, calendrical and athletic time periods. No device of comparable technological complexity is known until 1,000 years later. In 2005, a group of researchers known as the Antikythera Mechanism Research Project (AMRP) examined the 82 fragments of this badly corroded and brittle device with two modern technologies called Micro-Focus X-Ray Computed Tomography (CT) and Polynomial Texture Mapping (PTM,

Continue reading… Paul Iversen (CWRU Classics)

A Mellin Space Approach to Scattering in de Sitter Space

Boundary correlators in (anti)-de Sitter space-times are notoriously difficult beasts to tame. In AdS, where such observables are equivalent to CFT correlation functions, recent years have seen significant progress in our understanding of their structure owing to the development of numerous systematic techniques, many of which have drawn inspiration from the successes and the strengths of the scattering amplitudes programme in flat space. In dS however, the problem is more complicated owing to the time-dependence of the background and it is unclear how consistent time evolution is encoded in spatial correlations on the boundary.

Continue reading… Charlotte Sleight (IAS Princeton)

The Quest to Understand Neutrino Mass

Neutrinos play a central role in our understanding of the cosmos. From the observation of neutrino oscillation to the understanding of large-scale structure formation, massive neutrinos are a key ingredient to our understanding of the Universe at the smallest and largest scales. Recent experiments have precisely measured neutrino oscillation but fundamental questions about the nature and properties of neutrinos remain: Are neutrinos Majorana particles? What is the absolute mass of neutrinos, and why is it so small? Are there more than three neutrino species? In recent years, experiments measuring neutrinos from nuclear reactors and searching for rare nuclear decays have provided new insight to these questions.

Continue reading… Karsten Heeger (Yale University)

Twenty Years Later: Why No Clinical Quantum Dot Imaging Labels?

Quantum dots (QDs), semiconductor nanoparticles that fluoresce upon light excitation, were first
introduced for biological imaging in 1998. At the time, QDs were heralded as a revolutionary
product that would transform biological imaging. QDs have narrow emission bandwidths and
broad excitation spectra, enabling multiplexed imaging. Their fluorescence is tunable based on
QD size, permitting precise tuning of emission wavelength, and QDs are more resistant to
photobleaching than their molecular dye counterpoints. Yet, despite 20 years of research, there
are no clinically approved QD products and QDs remain a niche item used in specific research
situations.

Continue reading… Jessica Winter (Ohio State University)

Holographic Inflation: Symmetries in the relic pattern of primordial perturbations from a coherent quantum inflationary horizon

A reconciliation of quantum mechanics with gravity might be achieved in a holographic theory of quantum gravity, based on coherent states of covariant causal structures. This talk will review the properties of quantum-gravitational perturbations generated during cosmic holographic inflation, in which the inflationary horizon is a coherent quantum object, like the horizon of a black hole. A new analysis of cosmic anisotropy will be described, which shows evidence for some of the new symmetries.

Continue reading… Craig Hogan (University of Chicago)

Computational Photochemistry: Onwards with first-principles

Shane Parker, Department of Chemistry, Case Western Reserve University

Photochemistry lies at the heart of chemical, biological, and technological processes, from photosynthesis to solar electricity generation. To harness the potential of light to drive new chemistry, a detailed understanding of the mechanisms of photochemical reactions is necessary. However, this is difficult to impossible to achieve based on experimental observations alone (often spectroscopy). I will introduce nonadiabatic molecular dynamics (NAMD) simulations using time-dependent density functional theory (TDDFT), an increasingly important framework that can unravel the atomistic details of photochemical reactivities.

Continue reading… Shane Parker, Dept. of Chemistry, Computational Photochemistry: Onwards with first-principles

Ben Monreal (Physics) on the prize in Physics, Dan Scherson (Chemistry) on the prize in Chemistry and Abhishek Chakraborty (Department of Cancer Biology) on the prize in Physiology or Medicine. 

The 2019 Nobel Prize in Physics was awarded to Didier Queloz and Michel Mayor for their 1995 discovery of 51 Pegasi b, the first extrasolar planet.  The star 51 Pegasi is only a little different than the Sun, but 51 Pegasi b is like nothing previously known—it’s a Jupiter-like object, but in fiery hot orbit very close to the star.  Didier and Queloz, using a small telescope with an exquisite spectrograph,

Continue reading… The 2019 Nobel Prizes in Science

Not as big as a barn: Upper bounds on dark matter-nucleus cross sections

Critical probes of dark matter come from tests of its elastic scattering with nuclei. The results are typically assumed to be model independent, meaning that the form of the potential need not be specified and that the cross sections on different nuclear targets can be simply related to the cross section on nucleons. For pointlike spin-independent scattering, the assumed scaling relation is σχA∝A2μ2AσχN∝A4σχN, where the A2 comes from coherence and the μ2A≃A2m2N from kinematics for mχ≫mA. Here we calculate where model independence ends,

Continue reading… Matthew Digman (Ohio State University)

Title: Signatures of topological ground state degeneracy in Majorana islands

Abstract:

We consider a mesoscopic superconducting island hosting multiple pairs of Majorana zero-energy modes. The Majorana island consists of multiple p-wave wires connected together by a trivial (s-wave) superconducting backbone and is characterized by an overall charging energy $E_C$; the wires are coupled to normal-metal leads via tunnel junctions. Using a combination of analytical and numerical techniques we calculate the average charge on the island as well as non-local conductance matrix as a function of a p-wave pairing gap $\Delta_P$, charging energy $E_C$ and dimensionless junction conductances $g_i$.

Continue reading… Jukka Vayrynen, Microsoft Station Q, Santa Barbara , Signatures of topological ground state degeneracy in Majorana islands

Entropy as Disorder: History of a Misconception 

How did entropy morph from a quantifiable entity for finding the peak efficiency of a heat engine, into a synonym for “disorder”, and then into a catch-all name for anything bad?  Henry Adams (grandson of John Quincy Adams) plays a prominent role in this improbable story.

Continue reading… Dan Styer (Oberlin College)

Emergence and control in microbial communities:  steering bacterial pathogens through the phenotype space of multidrug resistance
 

Antibiotic resistance is a growing public health threat.  The emergence of resistance far outpaces the development of new drugs, underscoring the need for new strategies aimed at slowing the resistance threat.  In this talk, I’ll discuss our group’s ongoing work to understand the evolution of drug resistance in E. faecalis, an opportunistic bacterial pathogen, using quantitative experiments and theoretical tools from statistical physics and dynamical systems. By combining laboratory evolution with simple mathematical models, we show that unconventional strategies–including aperiodic drug dosing,

Continue reading… Kevin Wood (University of Michigan)

Continue reading… MLK Jr holiday, no seminar

New and old probes of the structure of the evolved Universe

The observed large scale distribution of galaxies and their peculiar motions (on top of the pure Hubble flow) are very well described in the framework of the standard Lambda Cold Dark Matter model. The model is founded on general relativity (GR) which in itself has recently gained substantial support by the detection of gravitational waves. Despite this success, observational data on large scales allow for deviations from the GR and the standard model. Any tiny deviation may have profound implications on fundamental physical theory of the Universe.

Continue reading… Adi Nusser (Technion)

A New Leading Mechanism for Neutrinoless Double-Beta Decay

… or how to attract the ire of the community. The neutrinoless double-beta decay of nuclei is essentially the only way to test lepton-number violation coming from the possible Majorana character of neutrinos. Tremendous effort is dedicated to its measurement and to reducing the theoretical uncertainty in the calculation of the nuclear matrix elements needed for its interpretation. Well, we increase the uncertainty.

Continue reading… Bira van Kolck (Institut de Physique Nucleaire d’Orsay and University of Arizona)

CANCELED

Plasmonic Bio-Assemblies and Metastructures:

Chirality, Coherent Transfer of Plasmons and Generation of

Hot Electrons 

Alexander O. Govorov

Department of Physics and Astronomy, Ohio University, Athens, USA; govorov@ohio.edu

Plasmonic nanostructures and metamaterials are very efficient at absorption and scattering of light. The studies to be presented in this talk concern special designs of hybrid nanostructures with electromagnetic hot spots, where the electromagnetic field becomes strongly enhanced and spatially concentrated. Overall, plasmonic nanostructures with hot spots demonstrate strongly amplified optical and energy-related effects,

Continue reading… (CANCELED) Alexander Govorov, Ohio University, Plasmonic Bio-Assemblies and Metastructures: Chirality, Coherent Transfer of Plasmons and Generation of Hot Electrons

Bispectrum Bias Loops and Power Spectrum Covariance

I will discuss recent progress in two topics in large-scale structure: 1) understanding galaxy bias beyond leading order in perturbation theory and its application to the bispectrum, and 2) how to model the covariance of the galaxy power spectrum multipoles analytically instead of using numerical simulations.

Continue reading… Roman Scoccimarro (NYU)

Solid State Materials Strategies for Quantum Information

Luke Bissell, Air Force Research Laboratory

In this talk I will first discuss the Air Force Research Laboratory (AFRL) strategy for investment in quantum information research, highlighting activities in the Information (Rome, NY), Space Vehicles and Directed Energy (Albuquerque, NM) and Materials and Manufacturing and Sensors Directorates (Dayton, OH). In the near term, AFRL is pursuing quantum sensing technologies for improved timekeeping and navigation in GPS denied environments. Mid-term investments are focused in architectures for quantum networks, including the entangled photon sources and quantum memories needed to realize them.

Continue reading… Luke Bissell, AFRL, Solid State Materials Strategies for Quantum Information

That Spin Zero Boson Changes Everything: The Future of the Energy Frontier in Particle Physics

The “Higgs Boson” discovery requires us to think differently about planning for the future of Particle Physics. While the decades-long confirmation of the Standard Model itself is an historic episode – as a dynamical model of nature, it is not helpful as a clear guide to the future. I will l review the features of the Standard Model that make it superb, but also  point out why it’s frustrating, and I’ll describe the hints that motivate us for the coming decades.

Continue reading… Raymond Brock (Michigan State University)

Linking Corrections to Entropy and Extremality

I will prove that the leading perturbative corrections to the entropy and extremality bounds of black holes are directly proportional to each other, generically.  This fact is intimately related to the Weak Gravity Conjecture, as I will discuss. The proof is purely thermodynamic and applies to systems beyond the gravitational realm.

Continue reading… Garrett Goon (CMU)

Quantum Algorithms for Collider Physics

As particle physics experiments continue to stretch the limits of classical computation, it is natural to ask about the potential future role of quantum computers.  In this talk, I discuss the potential relevance of quantum algorithms for collider physics.  I present a proof-of-concept study for “thrust”, a well-known collider observable that has O(N^3) runtime for a collision involving N final-state particles.  Thrust is a particularly interesting observable in this context, since it has two dual formulations, one which naturally maps to quantum annealing and one which naturally maps to Grover search. 

Continue reading… Jesse Thaler (MIT)

Particle Physics meets Machine Learning

Modern machine learning has had an outsized impact on many scientific fields, and particle physics is no exception.  What is special about particle physics, though, is the vast amount of theoretical and experimental knowledge that we already have about many problems in the field.  In this colloquium, I present two cases studies involving quantum chromodynamics (QCD) at the Large Hadron Collider (LHC), highlighting the fascinating interplay between theoretical principles and machine learning strategies.  First, by cataloging the space of all possible QCD measurements, we (re)discovered technology relevant for self-driving cars.  Second,

Continue reading… Jesse Thaler (MIT)

Topological defect structure and dynamics in 3D active nematics

Nematic liquid crystals, which are fluids with orientational order, may contain topological defects called disclinations where this order breaks down. While they’re undesirable in LCD screens, disclinations play an essential role in the dynamics of active nematics, non-equilibrium systems with internally driven flows coupled to nematic orientational distortions. Examples include cytoskeletal biofilaments with molecular motors, bacterial colonies, and some eukaryotic cellular tissues. In quasi-2D confinement, disclinations are point-like, and their pair-unbinding and motility drives the chaotic dynamics. In this talk, I will explore how the situation in 3D is even more complex.

Continue reading… Daniel Beller, University of California Merced, Topological defect structure and dynamics in 3D active nematics

Protein monomer dynamics control the first steps of aggregation and disease

Many neurodegenerative diseases, such as Parkinson’s and Alzheimer’s, are caused by uncontrolled aggregation of proteins.  While many aggregation-prone proteins ultimately form fibrillary structures, evidence suggests that early, unstructured aggregates are toxic to neurons.  The complexity and dynamics of unfolded protein ensembles may be the ultimate speed limit of folding and play a crucial role in aggregation. In my lab over the past several years we have investigated the reconfiguration dynamics of unfolded proteins by measuring the rate of intramolecular diffusion, the rate one part of the chain diffuses relative to another. 

Continue reading… Lisa Lapidus (Michigan State Univ)

The QCD Axion and Unification

The QCD axion is one of the most appealing candidates for the dark matter in the Universe. In this article, we discuss the possibility to predict the axion mass in the context of a simple renormalizable grand unified theory where the Peccei-Quinn scale is determined by the unification scale. In this framework, the axion mass is predicted to be in the range ma ≃ (3 − 13) × 10−9 eV. We study the axion phenomenology and find that the ABRACADABRA and CASPEr-Electric experiments will be able to fully probe this mass window.

Continue reading… Clara Murgui (IFIC, Valencia)

Collaborative efforts in materials physics

Due to the collaborative nature of the Holcomb group’s expertise, we explore many significant areas in materials science, including magnetism, magnetoelectricity, topological insulators and other quantum systems. This talk will focus on primarily our beamline efforts, as these often provide the most meaningful results. I will provide a few example cases and discuss our latest discovery of a new form of magnetism.
 

Host: Jesse Berezovsky

Continue reading… Mikel Holcomb, West Virginia University, Collaborative efforts in materials physics

Emerging photonic concepts such as optical metamaterials, metasurfaces, novel lasers, single-photon sources and other quantum photonic devices together with novel optical material platforms promise to bring revolutionary advances to information processing and storage, communication systems, energy conversion, imaging, sensing and quantum information technology. In pursuit of the next generation of photonic technologies, machine learning approaches have emerged as a powerful tool to discover unconventional optical designs and even uncover new optical phenomena. In this talk, various photonic design approaches as well as emerging material platforms will be discussed showcasting machine-learning-assisted topology optimization for efficient thermophotovoltaic metasurface designs as well as machine-learning enabled quantum optical measurements.

Continue reading… Alexandra Boltasseva (Purdue) Machine-Learning-Assisted Photonics: From Optimized Design to Quantum Measurements

Dark Matter Research with Bound Systems
 
My discussion will rest on three pillars. The first is an overview of bound states in dark sectors, and their implications for dark matter phenomenology, mass predictions and dark matter model building. The second is an exploration of new experimental techniques, which are needed to search for dark matter, which resides in a sector containing bound states. Finally, I will discuss some experimental observations based on bound states of ordinary matter, which can be used to constrain some of the introduced dark matter scenarios.

Continue reading… Juri Smirnov (Ohio State University)

Nonequilibrium spin currents and spin polarization in noncollinear antiferromagnetic insulators

Alexey Kovalev, Department of Physics, University of Nebraska, Lincoln

An ability to control spin is important for probing many spin related phenomena in the field of spintronics. Spin-orbit torque is an important example in which spin flows across magnetic interface and helps to control magnetization dynamics. As spin can be carried by electrons, spin-triplet pairs, Bogoliubov quasiparticles, magnons, spin superfluids, spinons, etc., studies of spin currents can have implications across many disciplines. In this talk, I first review the most common ways to generate spin flows and then concentrate on how spin can be controlled via magnons in insulating materials.

Continue reading… Alexey Kovalev, University of Nebraska Lincoln, Nonequilibrium spin currents and spin polarization in noncollinear antiferromagnetic insulators

 ***POSTPONED*** That Spin Zero Boson Changes Everything: The Future of the Energy Frontier in Particle Physics

The “Higgs Boson” discovery requires us to think differently about planning for the future of Particle Physics. While the decades-long confirmation of the Standard Model itself is an historic episode – as a dynamical model of nature, it is not helpful as a clear guide to the future. I will l review the features of the Standard Model that make it superb, but also  point out why it’s frustrating, and I’ll describe the hints that motivate us for the coming decades.

Continue reading… ***POSTPONED*** Raymond Brock (Michigan State Univ)

Phonons, free charge carriers, excitons and band-to-band transitions in beta Ga2O3 and related alloys determined by ellipsometry and optical Hall effect

Schubert1,2,3, A. Mock4, S. Knight1, M. Hilfiker1, M. Stokey1, V. Darakchieva2, A. Papamichail2, R. Korlacki1, M.J. Tadjer5, Z. Galazka6, G. Wagner6, N. Blumenschein7, A. Kuramata8, K. Goto8,9, H. Murakami9, Y. Kumagai8, M. Higashiwaki10, A. Mauze11, Y. Zhang11, J. S. Speck11

1Department of Electrical and Computer Engineering, University of Nebraska – Lincoln, Nebraska 68588, USA

2Department of Physics, Chemistry and Biology (IFM), Linkoping University, SE 58183 Linkoping, Sweden

3Leibniz Institute for Polymer Research,

Continue reading… Mathias Schubert, University of Nebraska-Lincoln, Phonons, free charge carriers, excitons and band-to-band transitions in beta Ga2O3 and related alloys determined by ellipsometry and optical Hall effect

EQUILIBRIUM AND NON-EQUILIBRIUM INTERFACIAL STATES OF LIQUID CRYSTALS IN CONTACT WITH BIOLOGICAL SYSTEMS

The generation, management and transduction of dynamic mechanical forces is one of the central sciences of living biological systems.  The development of synthetic soft matter that can exchange mechanical information with bacterial and mammalian cells has the potential to yield new classes of hybrid material systems that can report on and direct living biological systems.  This presentation will explore mechanical interactions of synthetic liquid crystalline materials and living systems in the context of molecular assemblies and cells.  The examples discussed in this presentation will illustrate how both equilibrium and non-equilibrium interfacial states of liquid crystals can give rise to new classes of functional soft materials that pass mechanical,

Continue reading… Nick Abbott (Biomolecular Engineering, Cornell)

Black-Hole Lattices as Cosmological Models

Challenges for modern cosmology include determining the influence the small-scale structure has in the universe on its large-scale dynamics and observations. With numerical relativity tools, finding and exploring cosmological models which are exact solutions to the Einstein equations will resolve all the non-linearities so that give us hints on quantifying the influence. In this talk, I will introduce Black-Hole Lattice models, which are subsets of relativistic discrete cosmological models. In particular, I will start from constructing those spacetimes and show what we can learn from exploring their properties.

Continue reading… Chi Tian (CWRU)

Continue reading… No seminar faculty meeting

The Physics of the Human Genome

Each of our cells contain 1 meter of DNA that is tightly wrapped to fit inside the ~5 micron wide nucleus of the cell. This highly condensed state of our DNA plays a central role in how the information in our genes is replicated, read and repaired. Yet, the physical mechanics by which genome organization regulates the processing of DNA remains a mystery. I will review what is currently understood about genomic organization with a focus on the first level of organization, the nucleosome – a 50 nm stretch of DNA tightly wrapped ~2 times around a protein core.

Continue reading… Michael Poirier (Ohio State University)

Electroweak measurements at electron-positron colliders as indirect searches for heavy neutrinos

Heavy neutrinos are part of many extensions of the Standard Model, in particular seesaw models that can explain the light neutrino masses and mixing. Future electron-positron colliders would greatly increase the precision of the measurements of electroweak processes. I will discuss how this improved precision offers new opportunities to search for the effects of heavy neutrinos. In particular, I will focus on indirect search strategies based on the modifications of the production cross-sections of W or Higgs bosons at linear collider. These searches are complementary to other observables and would allow to probe the multi-TeV mass regime at future colliders.

Continue reading… Cedric Weiland (University of Pittsburgh)

Quantum control of acoustic phonons

Superconducting qubits provide an excellent approach to building quantum computing systems, due to their good performance metrics and their easy lithographic scaling to large qubit numbers. In addition, these qubits provide unique opportunities as testbed systems for quantum communication as well as developing hybrid quantum systems. Here, I will discuss applications for superconducting qubits in generating and detecting individual phonons, in the form of quantum surface acoustic wave (SAW) excitations, and using these phonon states to generate remote quantum entanglement. Specifically, I will describe recent experiments [1,2] where we have demonstrated the use of reasonably high finesse acoustic Fabry-Perot structures to store acoustic phonon Fock states,

Continue reading… Andrew Cleland (U Chicago)

Searching for low mass dark matter particles at SNOLAB

90 years after its first evidence by F Zwicky, the nature of the dark matter of the Universe  is still unknown. There is a consensus it should be made of elementary particles but their search has been going on for several decades without success. Huge progress in sensitivity has been done, though,  thanks to new innovative detection techniques. Indeed some new techniques allow to enlarge the exploration of parameter space.  I will describe status of two projects I have developed, within international collaborations, thanks to a CERC grant in Canada,

Continue reading… Gilles Gerbier (Queen’s U)

Symmetry-Enforced Dirac Fermions in Nonsymmorphic α-Bismuthene 
 
Guang Bian, Department of Physics and Astronomy, University of Missouri
 
The discovery of graphene and topological insulators has stimulated enormous interest in two-dimensional electron gases with linear band dispersion. The vanishing effective mass and non-zero Berry phase of Dirac fermion-like states give rise to many remarkable physical properties such as extremely high mobility and zero-energy Landau levels. According to recent theoretical works, nonsymmorphic crystal symmetries can enforce the formation of Dirac cones, providing a new route to establishing Dirac states in 2D materials.  Here we will discuss our recent work on the realization of the symmetry-enforced Dirac fermions in nonsymmorphic α-bismuthene (Bi monolayer).

Continue reading… Guang Bian, University of Missouri, Symmetry-Enforced Dirac Fermions in Nonsymmorphic α-Bismuthene

Organization of clouds, and their impact on the climate system

Clouds are some of the largest uncertainties in weather and climate forecasting. They are also an interesting physical phenomenon, and despite having been studied and admired for millennia, there is still a lot that we do not understand, thanks to the multitude of physical processes. In the atmospheric system, clouds serve as a key component of a heat engine. The solar/infrared radiative fingerprint of clouds depends strongly on the droplet size distribution: Smaller droplets will result in a larger reflectivity, but also alters cloud lifetime. These effects are further complicated by organization and clustering of cloud fields.

Continue reading… Thijs Heus (Cleveland State University)

Massive Gravitons in Curved Spacetimes

This talk will cover various interesting topics that occur in massive spin-2 on various spacetimes
including de Sitter, anti-de Sitter, and flat space. In de Sitter, we examine what happens to massive
gravity as its mass approaches the partially massless value. In this limit, if the interactions are
chosen to be precisely those of the ’candidate’ non-linear partially massless theory, the strong
coupling scale is raised, giving the theory a wider range of applicability. In anti-de Sitter and flat
spacetime, we show how shift symmetries acting on the vector modes emerge from massive spin-2
theories fixing the non-linear structure and discuss whether these theories have amplitudes that
can be constructed via soft substracted recursion.

Continue reading… Laura Johnson (CWRU)

Mimicking cuprates with low-valence layered nickelates.

Antia Botana, Dept. of Physics, Arizona State University, Tempe, AZ

The physics behind high-temperature superconducting cuprates remains a defining problem in Condensed Matter Physics. One way of addressing this problem has been to search for alternative transition metal oxides with comparable structures and 3d electron count, proxies for cuprate physics. By means of electronic structure calculations, we propose low-valence layered nickelates as one of the closest analogs to cuprates yet reported. These materials possess a combination of traits that are widely considered as crucial ingredients for high-temperature superconductivity in cuprates: a square-planar nature,

Continue reading… Antia Botana, Arizona State University, Mimicking cuprates with low-valence layered nickelates.

The fall and rise of parity and the origin of (neutrino) mass

Continue reading… Goran Senjanovic (ICTP, Trieste)

Neutrino: chronicles of an aloof witness

As you read this, trillions of neutrinos from the sun are passing through every square cm of your body, doing no harm whatsoever. They convey information from the depth of the universe and have been present from its very birth. Neutrinos have captured the imagination of physicists from the time they were first conceived and have repeatedly provided a window into new physics.

A question stood out for decades: Are neutrinos massive like their seemingly inseparable electron siblings? It took almost seventy years to obtain the positive answer.

Continue reading… Goran Senjanovic (ICTP)

Strong CP violation: fancy and fact

Continue reading… Goran Senjanovic (ICTP, Trieste)

Photophysics as a Tool to Measure the Surface-State of Perovskite Nanoparticles

Jixin Chen, Department of Physics, Ohio University

The photoluminescence (PL) of organolead halide perovskites (OHPs) is sensitive to OHPs’ surface conditions and an effective way to report surface states. OHP is a hot semiconducting material that has a large potential in solar cells and LEDs. Photophysics describes the light-matter interactions in the materials using several phenomena such as absorption, exciton relaxation, emission quantum yield, photoblinking, and photodarkening/photobleaching. In this seminar, Dr. Chen will focus his talk on the photoblinking and photodarkening of perovskite nanoparticles.

Continue reading… Jixin Chen, Ohio University

Countering Weapons of Mass Destruction with Advanced Separations

Illicit nuclear activities such as the assembly of weapons of mass destruction or radiological dispersal devices (“dirty bombs”) pose a threat to national and world security.  National governments and world-wide organizations such as the International Atomic Energy Agency share an interest in monitoring and regulating international nuclear processes and materials. Nuclear forensics involves the examination of radioactive materials, using a variety of analytical techniques, with an end goal of determining the history and origin of the substance—guiding law-enforcement agencies as they determine “Whodunnit?” 

This talk will introduce the role of scientists in nuclear forensics and identify technological needs for fieldable radiation detection techniques.

Continue reading… Christine Duval (Chem Engineering, CWRU)

Born-Infeld Electrodynamics at One-Loop

The Born-Infeld model is an effective field theory of central importance describing the low-energy dynamics of massless gauge bosons on the world-volume of D-branes. Though it is in many ways exceptional in the universality class of models of nonlinear electrodynamics, several aspects of the physics of the Born-Infeld model remain mysterious. In this talk I will explain how aspects of the model, obscured in the traditional formulation of Lagrangian field theory, are clarified by directly studying the on-shell S-matrix. In particular in 3+1-dimensions, classical Born-Infeld has an electromagnetic duality symmetry which manifests in tree-level scattering amplitudes as the conservation of a chiral charge.

Continue reading… Callum Jones (University of Michigan)

Axis-dependent conduction polarity in layered materials 

Department of Chemistry and Biochemistry, The Ohio State University, Columbus

Layered and two-dimensional materials have emerged as one of the most exciting families of solid-state compounds, due to the plethora of unique physical phenomena found in these materials coupled with advances in the characterization of structure and properties down to the single layer scale. Here, we will describe our efforts in developing new families of these compounds, and our recent discovery of axis-dependent conduction polarity these materials.  Electronic materials generally exhibit a single majority carrier type, electrons or holes. 

Continue reading… Joshua Goldberger, The Ohio State University, Axis-dependent conduction polarity in layered materials

Striped and Superconducting Phases in Holography

There is a duality out of the framework of string theory that tells us, in certain cases, gravity can be thought of as emerging from the quantum mechanical degrees of freedom of a system. Remarkably, this relationship has not only given us a long sought after microscopic description of black holes and insights into the fabric of spacetime, but has also proven itself useful as a novel analytic toolset to investigate non-perturbative systems. Known as holography, this weak/strong coupling duality allows us to examine strongly coupled quantum systems by mapping them to perturbative, 

Continue reading… Erin Blauvelt (Lehigh University)

Cosmological Seed Magnetic Field from Inflation

A cosmological magnetic field of nG strength on Mpc length scales could be the seed magnetic field needed to explain observed few microG large-scale galactic magnetic fields. I first briefly review the observational and theoretical motivations for such a seed field, two galactic magnetic field amplification models, and some non-inflationary seed field generation scenarios. I then discuss an inflation magnetic field generation model. I conclude by mentioning possible extensions of this model as well as potentially observable consequences.

Continue reading… Bharat Ratra (Kansas State University)

Spatial Curvature, Dark Energy Dynamics, Neither, or Both?

Experiments and observations over the two last decades have persuaded cosmologists that (as yet undetected) dark energy is by far the main component of the energy budget of the current universe. I review a few simple dark energy models and compare their predictions to observational data, to derive dark energy model-parameter constraints and to test consistency of different data sets. I conclude with a list of open cosmological questions.

Continue reading… Bharat Ratra (Kansas State University)

Coupling Galaxy Evolution and the Epoch of Reionization

The Epoch of Reionization is a pivotal period in our cosmic history, representing the transition from a neutral post-recombination Universe into the fully ionized one we observe today. The procession of reionization is dictated by the fraction of ionizing photons, fesc, that escapes from galaxies to ionize the inter-galactic medium, with the exact value and functional form still an open question. I explore this question using the Semi-Analytic Galaxy Evolution (SAGE) model to generate galaxy properties, such as the number of ionizing photons emitted, and follow different possible Epoch of Reionization scenarios with a semi-numerical scheme.

Continue reading… Jacob Seiler (Swinburne University of Technology, Melbourne)

What Crystals Can Tell Us About the Origins of the Universe

Jumping from studying galactic scales to the nanoscale crystals in the laboratory might seem a gargantuan task. Common to both, however, is the concept of symmetry breaking and in particular the formation of topological defects – the materials equivalent of cosmic strings – in multiferroic crystals whose ferroelectric behavior enables the direct imaging of these defects. I also show how these crystals can be used to study an early-universe theory – the Kibble Zurek model – in the lab and demonstrate its verification for the first time in a crystal.

Continue reading… Sinead Griffin (Lawrence Berkeley Lab)

Designing materials: a synergistic process between theory, experiment and belief

Aldo Romero, Dept. of Physics and Atronomy, West Virginia University, Morgantown

The scientific process of designing materials has changed in the last ten years, as now theoretical methods have advanced to the level of becoming predictive, materials databases are increasing in size and experiments are more accurate and detailed. In this synergistic path, methods that combine all these methodologies are ideal, as long as we manage to condense the necessary design details into a series of fundamental material parameters. In this talk, I will discuss the atomistic process to design materials from scratch by using theoretical methods only based on the chemical composition and with little knowledge on the desired material or property of interest.

Continue reading… Aldo Romero, West Virginia University, Designing materials: a synergistic process between theory, experiment and belief

Moiré Patterns   in Two-Dimensional Materials

According to Wikipedia a moiré pattern (/mwɑːrˈeɪ/; French: [mwaˈʁe]) is a large scale interference pattern that is produced when an opaque regular pattern with transparent gaps is overlaid on another similar pattern with a different pitch or orientation.  Moiré patterns are ubiquitous in two-dimensional van der Waals materials in which the regular patterns are formed by two-dimensional crystals, differences in pitch are established by differences in lattice constants and differences in orientation, which can be controlled experimentally.  The electronic properties of two-dimensional semiconductor,

Continue reading… Allan MacDonald (U Texas Austin), Moiré Patterns   in Two-Dimensional Materials

Electroweak Baryogenesis, ACME II, and Dark Sector CP Violation
 
The origin of the matter-anti-matter asymmetry in the universe is a big puzzle for particle physics and cosmology. Baryogenesis mechanisms at the electroweak
scale are attractive for their testability at high-energy colliders and low-energy experiments. The recent measurement of electron electric dipole moment by ACME II sets stringent limit on weak scale CP violations and challenges the viable parameter space for successful electroweak baryogenesis in traditional models, such as two-Higgs doublet models and supersymmetry. In this talk, I will present our recent proposal of triggering electroweak baryogenesis with dark sector CP violation,

Continue reading… Yue Zhang (Fermilab)

Strong fluctuations in the relaxation of a 2D granular fluid

Horacio Castillo, Department of Physics and Astronomy, Ohio University

Glass transitions are associated with a rapid increase of the
relaxation time in a system as a function of an external parameter,
usually temperature or volume fraction. In the regime near the glass
transition, materials exhibit “dynamical heterogeneity”, i.e., the
presence of correlated fluctuations in the dynamical behavior of small
regions of the system, whose origin is still poorly understood. I will
discuss the results of large-scale numerical simulations of a two
dimensional granular fluid,

Continue reading… Horacio Castillo, Ohio University, Strong fluctuations in the relaxation of a 2D granular fluid

Cosponsored by the Cell Biology Program and the Departments of Chemistry and Physics

Kathleen Kash (Physics) on the prize in Physics, Gregory Tochtrop (Chemistry) on the prize in Chemistry and Alex Huang (Department of Pediatrics) on the prize in Physiology or Medicine. 

One-half of the 2018 Nobel Prize in Physics was awarded to Arthur Ashkin, “for the development of optical tweezers and their application to biological systems”. Optical tweezers use the radiation pressure of light to move small particles, and enabled Ashkin to manipulate living cells without damaging them. This work has had major impact in several fields,

Continue reading… The 2018 Nobel Prizes in Science: What were they given for?

Unification and Precision Measurements
 
Abstract: The Standard Model of particle physics may yet be unified into a deeper organizing principle. The gauge groups may unify into higher rank gauge group, and the Yukawa couplings might unify into a simplifying symmetry group. The key to assessing these unification prospects is precision measurements and related precision theory. The current status of unification, in its various guises, is discussed from the perspective of precision analysis. In addition, the prospects for further stress-testing the ideas at future experiment and through future theory work are also presented.

Continue reading… James Wells (University of Michigan-Ann Arbor)

Geometrically Frustrated Coulomb Liquids
V. Dobrosavljevic
Department of Physics and National High Magnetic Field Laboratory
Florida State University, Tallahassee, Florida 32306, USA

We show[1] that introducing long-range Coulomb interactions immediately lifts the massive
ground state degeneracy induced by geometric frustration for electrons on quarter-filled
triangular lattices in the classical limit. Important consequences include the stabilization of
a stripe-ordered crystalline (global) ground state, but also the emergence of very many lowlying
metastable states with amorphous “stripe-glass” spatial structures[2]. Melting of the
stripe order thus leads to a frustrated Coulomb liquid at intermediate temperatures,

Continue reading… Vladimir Dobrosavljevic, Florida State University, Geometrically Frustrated Coulomb Liquids

Quantum Processing in the Brain?

Building a laboratory quantum computer is now a billion dollar enterprise. But might we,
ourselves, be quantum computers? While maintaining quantum coherence on macroscopic time
scales is exceedingly unlikely in the warm wet brain, there is one exception: Nuclear spins. My
strategy is one of reverse engineering, seeking to identify the biochemical substrate and mechanisms
that could host such putative nuclear spin quantum processing. Remarkably, a specific neural qubit
and a unique collection of ions, molecules and enzymes can be identified, illuminating an apparently
single path towards quantum processing in the brain.

Continue reading… Matthew Fisher (KITP Santa Barbara)

The NANOGrav 11-year Data Set: New Insights into Galaxy Growth and Evolution

 
Precision Gravitational Astronomy
 
Abstract: 
 
The monumental measurement of gravity waves at LIGO has ushered in a new field of science with wide ranging implications, from Astrophysics and Cosmology to Nuclear Physics, Particle Physics and, of  course, General Relativity. However, our ability to extract information from the signal is bounded by our theoretical power. In this talk I will discuss how Effective Field Theory  techniques have been used to generate the highest precision analytic results for the signals generated by inspiraling binaries, emphasizing phenomenological benchmarks. I will also show how space-time geometry is actually encoded in gravitational S-matrix elements such that we may calculate forces between black holes with high precision using modern scattering amplitude techniques.

Continue reading… Ira Rothstein (Carnegie Mellon University)

Strange metals and black holes

The  ‘strange metal’, a state of matter formed by electrons in many modern materials, including the compounds which exhibit high temperature superconductivity. In this state, electrons quantum entangle with each other and conduct electric current collectively (rather than one-by-one, as in an ordinary metal like copper).  Quantum entanglement also has remarkable effects near the horizon of a black hole, leading to the Bekenstein-Hawking black hole entropy, and the Hawking temperature. Surprisingly, there is a deep connection between the nature of quantum entanglement in strange metals and black holes, and this has led to mutually beneficial insights. 

Continue reading… Subir Sachdev (Harvard University)

Giant telescopes, exoplanets, and astronomy in the 2020s

Controlled Synthesis and Emergent Properties of Heavy Transition Metal Oxides and Sulfides

Shixiong Zhang

Department of Physics, Indiana University, Bloomington, IN, USA

Heavy transition metal compounds (e.g. oxides and sulfides) often possess strong spin-orbit coupling (SOC) because of their high atomic numbers and electron correlation due to their compact d-orbitals. The competition and interplay of SOC and electron interactions is believed to induce a variety of novel electronic and magnetic ground states. In this talk, I will present our recent experimental work on two representative material systems, namely iridates and layered metal sulfides which exhibit a broad spectrum of intriguing physical properties.

Continue reading… Shixiong Zhang, Indiana University, Controlled Synthesis and Emergent Properties of Heavy Transition Metal Oxides and Sulfides

Continue reading… No Colloquium. Spring Break.

Continue reading… No Colloquium. APS March Meeting.

New Physics at Neutrino Telescopes

Abstract: The recent observation of high-energy neutrinos at the IceCube neutrino telescope has opened a new era in neutrino astrophysics.  Understanding all aspects of these events is very important for both Astrophysics and Particle Physics ramifications.  In this talk, I will discuss a few possible new physics scenarios, such as dark matter, leptoquarks and supersymmetry, that could be probed using the IceCube data.  I will also relate this to the puzzling observation of two upgoing EeV events recently made by the ANITA experiment, which were not seen by IceCube.

Continue reading… Bhupal Dev (Washington University)

From Giant Magnetoresistance to Nonlinear Magnetoresistance in Quantum Materials – An Exciting Journey with Spin

Shulei Zhang

Condensed Matter Theory Group, Materials Science Division, Argonne National Laboratory

Abstract:

Ever since its surprising emergence from relativistic quantum mechanics, spin has been known as an intrinsic angular momentum that plays a crucial role in electronic structure of matter. When the flows of spin and charge become intertwined through spin-orbit coupling or nontrivial magnetic structures, a host of intriguing magnetotransport phenomena emerge, such as giant magnetoresistance, spin Hall, topological Hall etc.

Continue reading… Shulei Zhang, Argonne National Laboratory, From Giant Magnetoresistance to Nonlinear Magnetoresistance in Quantum Materials – An Exciting Journey with Spin

Cosmology in the era of multi-messenger astronomy with gravitational waves 

Motivated by the exciting prospect of a new wealth of information arising from the first observations of gravitational and electromagnetic radiation from the same astrophysical phenomena, the Dark Energy Survey (DES) has established a search and discovery program for the optical transients associated with LIGO/Virgo events using the Dark Energy Camera (DECam). This talk presents the discovery of the optical transient associated with the neutron star merger GW170817 using DECam and discusses its implications for the emerging field of multi-messenger cosmology with gravitational waves and optical data.

Continue reading… Marcelle Soares-Santos (Brandeis University)

Functional quantum materials, including Mott insulators and high temperature superconductors, are at the forefront of modern materials science and condensed matter physics research. These materials are being actively explored for transformative technological applications, including efficient energy generation, storage and transmission. Understanding the fundamental mechanisms behind the exotic phases of matter emerging in quantum materials is a grand challenge, which must be overcome to maximize technological advancement.

            Due to the complexity of the many-electron problem, analytic theories become often unreliable and numerical treatment is required. Over the past decades, numerical analysis has become a very powerful tool for studying strongly correlated electron systems.

Continue reading… Hanna Terletska, Middle Tennessee State University,Understanding quantum materials using computational methods.

Breaking Mirror Hypercharge in Twin Higgs Models
 
The Twin Higgs is a novel framework to understand the stability of the Higgs mass in the face of increasingly stringent LHC bounds on colored top partners. Two principal structural questions in this framework concern the nature of the twin hypercharge gauge symmetry and the origin of the Z2 symmetry breaking needed to achieve the correct vacuum alignment. After an introduction to this framework, a simple extension of the Mirror Twin Higgs model with an exact Z2 symmetry is presented in which a new scalar field in the twin sector spontaneously breaks both twin hypercharge and Z2.  

Continue reading… Brian Batell (University of Pittsburgh )

In this talk I will discuss how synthetic photonic materials can be utilized to explore several non-Hermitian symmetries and their topological implications. Although difficult to access in high-energy physics and conventional condensed matter systems, these non-Hermitian symmetries can be realized in photonic materials with carefully arranged gain and loss elements. Therefore, such synthetic photonic materials provide an ideal platform to explore the ramification of these symmetries, including parity-time (PT) symmetry and non-Hermitian particle-hole symmetry, as well as the resulting novel optical phenomena and functionalities.

PT symmetric photonics [1] is one of the fastest growing fields in the past five years.

Continue reading… Li Ge, City University of New York, Exploring non-Hermitian symmetries and topology using synthetic photonic materials

Fundamental Physics and the Fifth Dimension 

The central aspirations and successes of Particle Physics will be reviewed against the backdrop of the twin pillars of modern physics,  Relativity and Quantum Mechanics. I will discuss current puzzles such as the Hierarchy Problem, the identity of Dark Matter, and the Matter/Antimatter Asymmetry and how their resolutions may connect to different incarnations of spacetime structure, from curved to higher-dimensional to supersymmetric.  I will describe how these in turn help drive a host of experimental ventures, from the Large Hadron Collider, to dark matter detection experiments, to gravitational wave cosmology. 

Continue reading… Raman Sundrum (University of Maryland)

Supersymmetry, Hidden Sectors, and Baryogenesis
 
Abstract:  Supersymmetry has been a primary target for the experiments at the Large Hadron Collider.  We review what the absence of supersymmetric signals thus far implies for supersymmetric extensions to the Standard Model.  We discuss ways in which supersymmetry might still have important consequences for our Universe — even if it does not completely explain the hierarchy between strength of gravity and the other forces.  As an example, we discuss how a supersymmetric extension might be responsible for generating the observed symmetry between matter and anti-mattter.

Continue reading… Aaron Pierce (University of Michigan-Ann Arbor)

Light-Matter Coupling in Molecular Materials

The combination of nanoscale fabrication technology along with the physical analogies between classical electromagnetic waves and quantum mechanical wave functions has opened the door to new classes of optical matter analogs and novel nano-optic metamaterials, such as photonic crystals and hyperbolic metamaterials, among others.  Such structures can be combined with real materials to achieve new forms of matter with a broad range of potential applications.  This presentation describes the incorporation of organic molecular excitonic materials in nanoscale optical cavities.  The resulting cavity polaritons exhibit behavior unique to organic materials and pave the way for room temperature quantum optical structures and effects. 

Continue reading… Ken Singer (CWRU Physics)

Constraining the gravitational sector with black hole perturbations

A Physicist on Mars

Mars, our nearest neighbor outward in the solar system, is a planet that has fascinated humans for hundreds of years.  Physicist Geoffrey A. Landis of the NASA Glenn Research Center will discuss NASA’s rover missions to Mars, including the mission of the Mars Exploration Rovers, which have been traversing the surface of Mars for a mission of seventeen years, carrying a suite of physics-based instrumentation including hyperspectral cameras, Mössbauer spectrometry, and alpha-induced x-ray fluorescence. This talk will present some results of the many missions that have been (and still are) exploring Mars,

Continue reading… Geoffrey Landis (NASA Glenn)

Searching for the dark sector in neutrino detectors
 
Abstract: Dark matter has thus far eluded attempts to determine its non-gravitational interactions, putting strong constraints on a minimal dark sector. I present models of non-minimal dark sectors that could elude current searches, but be seen in current or near future neutrino experiments. I begin by presenting a comprehensive, ongoing phenomenological study of models in which dark matter can annihilate into other forms of dark matter, leading to a flux of energetic (boosted) dark matter (BDM). Such dark matter could deposit enough energy to be detected in large neutrino detectors such as Super-Kamiokande and DUNE.

Continue reading… Joshua Berger (University of Pittsburgh)

“Defects” as Qubits in SiC: “Inverted Atoms”

There is often a natural assumption that a “perfectly structured” material is required to produce “perfect functioning” of a device, where the function may relate to precision sensing, or the storing or transmission of information. Recently, however, there has been excitement about the performance of defects in crystalline semiconductors such as diamond and SiC. The defects are deviations from perfect, periodic crystalline order, yet can manifest optical emission at a variety of wavelengths, distinctively coupled to long spin coherence times. Rather than focusing on the defect within a semiconductor,

Continue reading… Evelyn Hu (Harvard University)

Shift Symmetries in (Anti) de Sitter Space

The two mathematical careers of Emmy Noether

A talk describing Emmy Noether’s life, how she encountered the conservation problem in General Relativity, and how her theorem on it relates to her later larger plan to reorganize all of pure mathematics.

Continue reading… Colin McLarty (CWRU Philosophy)

Tau-philic dark matter coannihilation at the LHC and CLIC 

Abstract: We will discuss a set of simplified models of dark matter with three-point interactions between dark matter, its coannihilation partner and the Standard Model particle, which we take to be the tau lepton. The contribution from dark matter coannihilation is highly relevant for a determination of the correct relic abundance. Although these models are hard to detect using direct and indirect detection, we will show that particle colliders can probe large regions in the parameter space. Some of the models discussed are manifestly gauge invariant and renormalizable,

Continue reading… Alexis D. Plascencia (CWRU)

Abstract: 

Host: Covault

Continue reading… Stephane Coutu (Penn State)

Topological defects in nematic liquid crystals: playground of fundamental physics

Samo Kralj

1Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia

2Solid State Department, “Jožef Stefan” Institute, Jamova 39, Ljubljana, Slovenia

       Topological defects (TDs) are an unavoidable consequence of continuous symmetry breaking phase transitions [1]. They appear at all scales of physical systems, including particle physics, condensed matter and cosmology. Due to their topological origin they display several universalities that are independent of the systems’ microscopic details.

Continue reading… Samo Kralj,Josef Stefan Institute in Ljubljana and University of Maribor, Slovenia, Topological defects in nematic liquid crystals: playground of fundamental physics

Continue reading… Mark Griswold (CWRU Radiology)

Loop induced inflationary non-Gaussianites that give rise to an  enhanced galaxy power spectrum at small wave-vectors
 
Abstract:  I outline the calculation of non-Gaussian mass density fluctuations that arise from one-loop Feynman diagrams in a de Sitter background.  Their impact on the distribution of galaxies on very large length scales (i.e. l > 200/ h Mpc) is discussed. The role that  symmetries of the de Sitter metric play in determining the form of the power spectrum,  bi-spectrum and tri-spectrum of primordial curvature perturbations is emphasized.

Host: Fileviez Perez

Continue reading… Mark B. Wise (Caltech)

 Effective field theories for dark matter direct detection

Abstract:

I will discuss the nonperturbative matching of the effective field theory describing dark matter interactions with quarks and gluons to the effective theory of nonrelativistic dark matter interacting with nonrelativistic nucleons. In general, a single partonic operator already matches onto several nonrelativistic operators at leading order in chiral counting. Thus, keeping only one operator at the time in the nonrelativistic effective theory does not properly describe the scattering in direct detection. Moreover, the matching of the axial–axial partonic level operator, as well as the matching of the operators coupling DM to the QCD anomaly term,

Continue reading… Jure Zupan (University of Cincinnati)

High entropy alloys: mechanical properties and phase stability
Maryam Ghazisaeidi, Department of Materials Science and Engineering, Ohio State University

The term “High entropy” alloys (HEA) refers to a relatively new class of multicomponent—usually
five or more—metallic alloys in equal or near equal atomic concentrations. Instead of ordered
intermetallics, expected from classical physical metallurgy, some HEA systems strikingly crystalize
as single phase solid solutions with simple crystal structures. The complex compositions of these
alloys, and their derivatives, lead to unique properties. They also encourage new ways of viewing
fundamentals of physical metallurgy,

Continue reading… Maryam Ghazisaeidi, Ohio State University, High entropy alloys: mechanical properties and phase stability

The Dark Side of Cosmic Dawn.

Dark matter constitutes more than 5/6 of the matter in the universe, but its nature and interactions remain one of the great puzzles of fundamental physics. Dark matter collisions or decays, occurring throughout the universe’s past, have the potential to produce high-energy particles; such particles may already have reshaped the history of our cosmos, leaving traces of their existence in ionization and heating of the intergalactic medium. I will discuss possible signatures of new dark matter physics in cosmological observations, from the cosmic dark ages to the epoch of reionization,

Continue reading… Tracy Slatyer (MIT)

First Results from the ABRACADABRA-10cm Prototype

The evidence for the existence of Dark Matter is well supported by
many cosmological observations. Separately, long standing problems
within the Standard Model point to new weakly interacting particles to
help explain away unnatural fine-tunings. The axion was originally
proposed to explain the Strong-CP problem, but was subsequently shown
to be a strong candidate for explaining the Dark Matter abundance of
the Universe. ABRACADABRA is a proposed experiment to search for
ultralight axion Dark Matter, with a focus on the mass range
10^{-14} ~<

Continue reading… Jonathan Ouellet (MIT)

Rare-earth nitrides; semiconductors, spin/orbit magnetism, tunnelling MRAM, superconductivity

Joe Trodahl

 MacDiarmid Institute for Advanced Materials and Nanotechnology

Victoria University of Wellington New Zealand

Controlling the flow of electronic spin in addition to the charge promises speed and power demand advantages. However, there are as yet few “spintronic” devices on the market, in part due to a lack of intrinsic ferromagnetic semiconductors that would permit full exploitation of the coupled spin/charge technology. To date the only full series of such materials are the mononitrides of the lanthanides, the 14 rare-earth elements.

Continue reading… Joe Trodahl, Victoria University of Wellington, Rare-earth nitrides; semiconductors, spin/orbit magnetism, tunnelling MRAM, superconductivity

Plasmons at the Interface Between Physics and Cancer Nanotechnology: The Next Big Thing will be at the Nanoscale

In recent years significant efforts have been made to design and fabricate functional nanomaterials for biomedical applications. These research activities unlocked a complete new research field known as nano-biophotonics. Extreme optics of artificial materials characterized by hyperbolic dispersion allowed to access new physical effects and mechanisms. The unbound isofrequency surface of hyperbolic metamaterials opened the way for virtually infinite photonic density of states and ultrahigh confinement of electromagnetic fields in multilayered nanostructures. This has lead to speed up significantly the spontaneous emission of quantum emitters1,

Continue reading… Pino Strangi (CWRU Physics)

3D plasmonic nanostructures for biology and medicine

Francesco De Angelis

Istituto Italiano di Tecnologia, Genoa, Italy

In this talk we will show our last achievements and future perspectives of distinct class of plasmonic devices devoted to biological and medical applications. Among them, we will introduce the concept of meta-electrodes, namely a nanostructured surface that can work as electrode, a broad band plasmonic antenna, and optimal cellular interface (see Figure 1). We show that meta-electrodes combined with commercial CMOS technology enable high quality intracellular electrical signals on the large network scale of human neuron and cardiomyocytes .

Continue reading… F. De Angelis, Istituto Italiano di Tecnologia, Genoa, Italy, 3D plasmonic nanostructures for biology and medicine

Flat Optics: from Metalenses to New Polarization Optics and New Routes to Vector Beam Generation 

Arrays of optically thin, sub-wavelength spaced optical elements (meta surfaces) have major potential for wavefront shaping through local control of the phase, amplitude and polarization of light [1]. Flat optics has emerged from this approach [2] with the goals of replacing refractive lenses in most applications requiring aberrations’ correction [3,4] as well as conventional phase plates used in polarization optics [5] and last but not least of providing a new path to the creation of structured light [6]. 

Continue reading… Federico Capasso (Harvard Univ)

Primordial black holes in the wake of LIGO

The detection of gravitational waves from the merger of black holes of ~30 solar masses has reignited the interest of primordial black holes (PBHs) as the source of the dark matter in the universe. We will review the existing constraints on the abundance of PBHs and the implications for several fundamental physics scenarios. A small relic abundance of heavy PBHs may play and important role in the generation of cosmological structures, and we will discuss how such a PBH population can be generated by the collapse of axionic topological defects.

Continue reading… Francesc Ferrer (Washington University)

Quantum Magnonics in V[TCNE]2

The study of quantum coherent magnonic interactions relies implicitly on the ability to excite and exploit long lived spin wave excitations in a magnetic material. That requirement has led to the nearly universal reliance on yittrium iron garnet (YIG), which for half a century has reigned as the unchallenged leader in high-Q, low loss magnetic resonance, and more recently in the exploration of coherent quantum coupling between magnonic and spin [1] or superconducting [2] degrees of freedom. Surprisingly, the organic-based ferrimagnet vanadium tetracyanoethylene (V[TCNE]2) has recently emerged as a compelling alternative to YIG.

Continue reading… Ezekiel Johnston-Halperin, The Ohio State University, Quantum Magnonics in V[TCNE]2

Conserving Helium: A story of MgB2 superconducting wire and MRI magnets

The fabrication of MgB2 superconducting wire has enabled the development of novel magnet designs for MRI systems. Compared to MRI magnets in use today, which are submerged in a bath of liquid helium, the higher critical temperature (39K) of the MgB2 facilitates conduction cooling which reduces the use of liquid helium by a factor of 100 or more. In collaboration with Hyper Tech Research, a world leader in the manufacture of MgB2 wire, and the Center for Superconducting and Magnetic Materials at the Ohio State University,

Continue reading… Mike Martens (CWRU Physics)

The art of neutrino detection: What does it take, and why?

Neutrinos are fundamental blocks of matter. As we’ve learned more and more about them and their properties over the past few decades, we’ve also been led to some important questions about the role of neutrinos in the evolution of our universe; we have also gathered perplexing evidence that makes us question our assumptions about neutrinos in the first place. This talk will review what we know about neutrinos, questions about them that we have yet to answer, and some challenging engineering quests we have embarked on in order to try and settle those questions.

Continue reading… Georgia Karagiorgi (Columbia University)

Multivariate Dependent Halo and Galaxy Assembly Bias

Galaxies form in dark matter halos, and their properties and
distributions are connected to the host halos. With a prescription of
the galaxy-halo relation and the theoretically known halo clustering
(e.g., from N-body simulations), galaxy clustering data from large
galaxy surveys can be modeled to learn about galaxy formation and
cosmology. In the above halo-based model, it is usually assumed that
the statistical distribution of galaxies inside halos only depends on
halo mass. However, it is found that in addition to mass halo
clustering also depends on the formation history and environment of
halos,

Continue reading… Xiaoju Xu (University of Utah)

Sergey Kravchenko,

Northeastern University

The latest developments in the field of the metal-insulator transition in 2D

Abstract:
Ignited by the discovery of the metal-insulator transition, the behavior of low-disorder two-dimensional (2D) electron systems is currently the focus of a great deal of attention. In the strongly-interacting limit, electrons are expected to crystallize into a quantum Wigner crystal (Wigner, 1934), but no definitive evidence for this effect has been obtained despite much experimental effort over the years. Now we have found two-threshold voltage-current characteristics with a dramatic increase in noise between the two threshold voltages.

Continue reading… Sergey Kravchenko, Northeastern University, The latest developments in the field of the metal-insulator transition in 2D

Fundamental Physics with the Simons Observatory

The Simons Observatory is a new cosmic microwave background experiment being built on Cerro Toco in Chile, due to begin observations in the early 2020s. I will describe the scientific goals of the experiment, motivate its design, and forecast its performance. The Simons Observatory will measure the temperature and polarization anisotropy of the cosmic microwave background with arcminute resolution over approximately 40% of the sky in six frequency bands: 27, 39, 93, 145, 225 and 280 GHz. In its initial phase, three small-aperture (0.5-meter diameter) telescopes and one large-aperture (6-meter diameter) telescope will be fielded.

Continue reading… Brian Keating (UC San Diego)

New Results from the South Pole Telescope

I will give an overview of the South Pole Telescope (SPT), a 10-meter diameter telescope at the South Pole designed to measure the cosmic microwave background (CMB).  The SPT recently completed 10 years of observations, over which time it has been equipped with three different cameras: SPT-SZ, SPTpol, and SPT-3G. I will discuss recent results from the SPT-SZ and SPTpol surveys, including: an update on the SPT Sunyaev-Zel’dovich (SZ) cluster survey, and joint analyses with the optical dark energy survey (DES); a comparison of CMB measurements between SPT-SZ and the Planck satellite;

Continue reading… Brad Benson (University of Chicago)

2018 Michelson Postdoctoral Prize Lecture 3: Colloquium 

Indirect Searches for Weakly-Interacting Massive Particles

Recent observations at gamma-ray and radio energies, as well as local observations of charged cosmic-rays, have placed increasingly stringent constraints on the annihilation cross-section of Weakly Interacting Massive Particle (WIMP) dark matter. Excitingly, these studies have begun to rule out the infamous “thermal annihilation cross-section”, where WIMP models are expected to naturally obtain the observed relic abundance. As expected when multiple cutting-edge observations coincide, there is currently tension between different studies. For example, strong limits from gamma-ray searches in dwarf-spheroidal galaxies lie in significant tension with dark matter explanations for the observed “Galactic Center excess” observed near the center of the Milky Way.

Continue reading… Tim Linden (Ohio State University)

2018 Michelson Postdoctoral Prize Lecture 2

The Rise of the Leptons: Emission from Pulsars will Dominate the next Decade of TeV Gamma-Ray Astronomy

HAWC observations have detected extended TeV emission coincident with the Geminga and Monogem pulsars. In this talk, I will show that these detections have significant implications for our understanding of pulsar emission. First, the spectrum and intensity of these “TeV Halos” indicates that a large fraction of the pulsar spindown energy is efficiently converted into electron-positron pairs. This provides observational evidence necessitating pulsar interpretations of the rising positron fraction observed by PAMELA and AMS-02.

Continue reading… Tim Linden (Ohio State University)

Michelson Postdoctoral Prize Lecture 1

Astrophysical Signatures of Dark Matter Accumulation in Neutron Stars

Over the past few decades, terrestrial experiments have placed increasingly strong limits on the dark matter-nucleon scattering cross-section. However, a significant portion of the standard dark matter parameter space remains beyond our reach. Due to their extreme density and huge gravitational fields, neutron stars stand as optimal targets to probe dark matter-nucleon interactions. For example, over the last few years, the mere existence of Gyr-age neutron stars has placed strong limits on models of asymmetric dark matter. In this talk,

Continue reading… Tim Linden (Ohio State University)

The WIMP is Dead. Long Live the WIMP!
 
Abstract: Although weakly interacting massive particles (WIMPs) have long been the leading class of candidates for the dark matter of our universe, the lack of a confirmed detection of these particles has left the community increasingly skeptical of their existence. In this talk, I will ask the following questions: How surprised should we be that WIMPs have not yet been detected? What assumptions might we change in order to explain the lack of any clear signals of dark matter? In light of the current experimental situation, what are the prospects for future direct,

Continue reading… Dan Hooper (Fermilab)

Cosmological Observables via Non-equilibrium Quantum Dynamics in Non-stationary Spacetimes

Abstract: 

In nearly all cases cosmological observables associated with quantum matter fields are computed in a general approximation, via the standard irreducible representations found in the operator formalism of particle physics, where intricacies related to a renormalized stress-energy tensor in a non-stationary spacetime are ignored. Models of the early universe also include a hot, dense environment of quantum fields where far-from-equilibrium interactions manifest expressions for observables with leading terms at higher orders in the coupling. A more rigorous treatment of these cosmological observables may be carried out within the alternative framework of algebraic quantum field theory in curved spacetime,

Continue reading… Mahmoud Parvizi (Vanderbilt University)

 DNA folding thermo/dynamics with a twist

Alkan Kabakcioglu, Koc University, Istanbul

DNA denaturation is possibly one of the earliest problems in biophysics that grabbed the attention of statistical physicists. The nature of the folding/melting transition has been subject to debate since 60’s until a breakthrough in the past decade mostly settled the question. We recently readdressed the problem for circular DNA (which has a topologically imposed, fixed linking number due to helicity) and found that the melting behavior is qualitatively different from that of the unconstrained DNA with freely dangling ends.

Continue reading… Alkan Kabakcioglu, Koc University, DNA folding thermo/dynamics with a twist

Manipulation of Topological Defects in Liquid Crystals

 A topological defect (TD) occurs at a wall, line, or point where the relevant order parameter — in our case the liquid crystal’s orientational order parameter — becomes ill-defined, and where this singularity cannot be removed by varying the order parameter continuously. Studies of TDs can be used to obtain values of elastic constants and surface tension, and can serve as an important signature when determining the symmetry of phases. Defect dynamics provide another important field of study, as defect motion is extremely sensitive to boundary effects and provides information about surfaces and impurities.

Continue reading… Charles Rosenblatt (CWRU Physics)

The Dark Universe in the Gravitational Wave Era
Evidence shows that we live in a universe where 95% of the matter and energy is of unknown nature. Right from the onset, Gravitational Wave (GW) astronomy is shaping our understanding of the dark universe in several ways: GW signals of black hole mergers have resurrected the idea of Dark Matter being made of primordial black holes, while multi-messenger GW astronomy has generated novel ways to test Dark Energy and the fundamental properties of gravity. I will discuss the impact of gravitational waves on the landscape of gravitational theories,

Continue reading… Miguel Zumalacarregui (UC Berkeley & IPhT Saclay)

Continue reading… no seminar/faculty meeting

Missile Defense and Space Weapons

Missile defenses and space weapons have been pursued at modest levels for many decades, but both are poised to see an enormous increase in funding and scope in the United States. Developments in North Korean nuclear and missile programs are providing justification to build more of existing missile defense systems as well as new types of systems.  And recent policy directs the Pentagon to create a Space Force and to begin building both offensive and defensive space systems.

Missile defense and space weapons are also closely related technologically. Defense systems designed to target ballistic missiles have inherent capabilities as anti-satellite weapons.

Continue reading… Laura Grego (Union of Concerned Scientists)

Chiral Dark Sectors, Neutrino Masses, and Dark Matter

I discuss the hypothesis that there are new chiral fermions particles that transform under a new gauge group. Along the way, I present one mechanism for constructing nontrivial, chiral gauge theory and explore the phenomenology – mostly related to nonzero neutrino masses and the existence of dark matter – associated to a couple of concrete example.

Host: Fileviez Perez

Continue reading… Andre De Gouvea (Northwestern Univ.)

The Brave nu World

I review the current theoretical and phenomenological status of neutrino physics. I will discuss our current understanding of neutrino properties, open questions, some new physics ideas behind nonzero neutrino masses, and the challenges of piecing together the neutrino mass puzzle. I will also comment on the new physics reach of the current and the next generation of neutrino oscillation experiments.

Continue reading… Andre De Gouvea (Northwestern University)

SHINING LIGHT INTO COSMIC DARK AGES

The first billion years is the least-explored epoch in cosmic history. The first claimed detection of the 21 cm line of neutral hydrogen by EDGES (announced at the end of February this year) – if confirmed – would be the first time ever that we witness star formation at cosmic dawn. Join Dr. Fialkov as she discusses theoretical modeling of the 21 cm signal, summarizes the status of the field after the EDGES detection, and shares thoughts on prospects for future detections of this line.

Host: Starkman

Continue reading… Anastasia Fialkov (Harvard Univ.)

High Energy Neutrino Astronomy through Radio Detection 

Multimessenger astronomy has entered an exciting new era with the recent discovery of both gravitational waves and cosmic neutrinos.  I will focus on neutrinos as particles that can uniquely probe cosmic distances at the highest energies.  While optical Cerenkov radiation has been used for decades in neutrino experiments, the radio Cerenkov technique has emerged in the last 15 years as the most promising for a long-term program to push the neutrino frontier by over a factor of 1000 in energy.   I will give an overview of the current status and future of the radio neutrino program,

Continue reading… Amy Connolly (The Ohio State University)

Fitting amu and B physics anomalies with a Z’ and a Vector-like 4th family in the Standard Model

The Standard Model is very successful.  Nevertheless, there are some, perhaps significant, discrepancies with data.

A particularly interesting set of discrepancies hints at new physics related to muons. I will review the data and recent

NP models trying to fit the data.  Then I will discuss a very simple model which is motivated by heterotic string constructions.

Continue reading… Stuart Raby (Ohio State University)

Report from the International Conference on Women in Physics: Reaching Towards Equity and Inclusion
 
In July 2017, I was one of the US delegates to the IoP International Conference on Women in Physics, held in Birmingham, UK. The conference brought together feminist scientists from around the world to share their work and inspiration, to mentor each other, and to share best practices. Each country’s delegation summarized the status and main obstacles for women physicists in their country. In this talk, I will briefly describe the status within several countries, then explain the issues presented in the US country poster: implicit bias,

Continue reading… Laura Gladstone (CWRU Physics)

First light at the IceCube Neutrino Observatory
The IceCube Neutrino Observatory, the world’s largest neutrino detector, monitors a cubic kilometer of glacial ice below the South Pole Station to search for very high energy neutrinos from the astrophysical accelerators of cosmic rays.  Since its commissioning in 2011, IceCube has discovered a flux of TeV-PeV scale astrophysical neutrinos, at a level with significant implications for our understanding of the dynamics of the non-thermal universe.  The sources of this flux have remained elusive, however.  In the last six months, hints to the identity of at least some of the sources may have begun to emerge,

Continue reading… Tyce DeYoung (Michigan State University)

Orbital Selective Mott Transition in Thin Film VO2

Wei-Cheng Lee

Department of Physics, Applied Physics, and Astronomy, Binghamton University – SUNY

In this talk, evidences of strain-induced modulation of electron correlation effects in the rutile phase of epitaxial VO2/TiO2 will be presented. The strain is engineered by different growth orientations (001), (100), and (110). We find that the hard x-ray photoelectron spectroscopy (HAXPES) reveals significant suppression of the density of states at the Fermi energy in (100) and (110) samples at a temperature well above the metal-insulator transition temperature, but not in the (001) sample.

Continue reading… Wei-Cheng Lee, Binghamton University-SUNY, Orbital Selective Mott Transition in Thin Film VO2

Learning to perturb the evolutionary mechanisms driving drug resistance in cancer and microbes: an integrated theoretical and experimental approach.

The evolution of resistance remains an elusive problem in the treatment of both cancer and infectious disease, and represents one of the most important medical problems of our time. While the illnesses are different on several non-trivial levels including timescale and complexity, the underlying biological phenomenon is the same: Darwinian evolution. To comprehensively approach these problems, I have focussed my attention on building a broad suite of investigations centered around the causes and consequences of the evolutionary process in these contexts.

Continue reading… Jacob Scott (Cleveland Clinic)

Computationally Probing Large Structures
We can constrain cosmological parameters by measuring patterns in the large scale structure of our universe, which are governed by the competition between gravitational collapse and the accelerated expansion of our universe.  The most massive collapsed structures are clusters of galaxies, comprised of hundreds to thousands of galaxies.  For galaxy clusters, the telltale cosmological pattern is simply their number count as a function of mass and time.  In this talk, I will discuss the challenges in using galaxy clusters as a probe for cosmology.  We address these challenges through computational methods that explore galaxy formation processes such as energy feedback from active galactic nuclei,

Continue reading… Camille Avestruz (Kavli Institute for Cosmological Physics, University of Chicago)

Continue reading… Fac. meeting

Ocean Worlds: from Familiar to Exotic and Extreme Planets
 
Water is a common molecule in the the galaxy and an abundant bulk component of planets – like Neptune, far from their stars. Liquid water – a precious solvent, might be significantly more rare. Exoplanet exploration is both motivated by the search for surface liquid water and is helping us understand the wide diversity of ocean worlds. Such understanding is necessary if we are to succeed in the search for planetary conditions that could lead to the emergence of life.

Continue reading… Dimitar Sasselov (Harvard University)

The Broken Symmetry of Music: Applying Statistical Physics to Understand the Structure of Music

The ubiquity of music throughout history and across cultures raises a fundamental question: Why is this way of arranging sounds such a powerful medium for human artistic expression? Though there are myriad musical systems and styles, there are certain characteristics that are nearly universal, including a restriction to a discrete set of sound frequencies (pitches). In this talk, I will present a bottom-up approach to a theory of musical harmony, starting from two basic (and conflicting) principles: a system of music is most effective when it 1.

Continue reading… Jesse Berezovsky (CWRU Physics)

Collider Physics for Inflation
Cosmological correlation functions encode the spectrum of particles during inflation, in analogy to scattering amplitudes in colliders. Particles with masses comparable to the Hubble scale lead to distinctive signatures on non-Gaussianities that reflect their masses and spins. In addition, there exists a special class of partially massless particles that have no flat space analog, but could have existed during inflation. I will describe their key spectroscopic features in the soft limits of correlation functions, and discuss scenarios in which they lead to observable non-Gaussianity.

Continue reading… Hayden Lee (Harvard University)

Using Ions to Control Transport in 2D Materials

Susan Fullerton, University of Pittsburgh

Electrostatic gating of two-dimensional (2D) materials with ions is an effective method to achieve high carrier density (10^13 – 10^14 cm^-2) and excellent gate control by creating an electric double layer (EDL) with large capacitance density (>2 μF/cm^2). I will review our use of EDL gating to investigate transport properties of 2D materials including MoTe2, MoS2 and WSe2, and introduce new device concepts that employ EDL gating as an active device component. These include a monolayer electrolyte for application in flash memory,

Continue reading… Susan Fullerton, University of Pittsburgh, Using Ions to Control Transport in 2D Materials

Quantum Monte Carlo modeling of real materials

Olle Heinonen, Argonne National Laboratory

Because of recent advances in algorithms and hardware, it is now possible to do quantum Monte Carol simulations of real materials systems, such as correlated oxides, for which standard density functional theory methods have well-known problems. I will here briefly introduce variational and diffusion Monte Carlo methods, and then discuss some results for correlated oxides as well as for some chemical systems. I will end with discussing on-going developments and an outlook towards the future.

Continue reading… Olle Heinonen, Argonne National Laboratories, Quantum Monte Carlo modeling of real materials

Continue reading… TBA

 Nonlinear photocurrents in two-dimensional ferroelectrics and beyond

Benjamin Fregoso, Dept. of Physics, Kent State University

Abstract:

In recent years, it has become clear the need for efficiently harvesting solar energy. Unfortunately, silicon-based solar cells with high efficiency are very costly. These devices rely on pn-junctions to separate positive and negative charge carries. I this talk, I explore a less known (but very interesting) nonlinear optical effect, so-called `shift current’, to generate large photocurrent beyond the pn-junction paradigm. I will describe the shift-current mechanism in insulators and ferroelectrics and its relation to spontaneous electric polarization.

Continue reading… Benjamin Fregoso, Dept of Physics, Kent State University, Nonlinear photocurrents in two-dimensional ferroelectrics and beyond

The Latest Results from the HAWC Very High-Energy Gamma-ray Survey
The High Altitude Water Cherenkov (HAWC) observatory, located in central
Mexico, is conducting a wide-angle survey of TeV gamma rays and cosmic
rays from two-thirds of the sky. TeV gamma rays are the highest energy
photons ever observed and provide a unique window into the non-thermal
universe. These very high energy photons allow HAWC to conduct a broad
science program, ranging from studies of particle acceleration in the
Milky Way to searches for new physics beyond the Standard Model. In this
talk,

Continue reading… Segev BenZvi (University of Rochester)

Quantum speed limits: from Heisenberg’s uncertainty principle to optimal quantum control

One of the most widely known building blocks of modern physics is Heisenberg’s indeterminacy principle. Among the different statements of this fundamental property of the full quantum mechanical nature of physical reality, the uncertainty relation for energy and time has a special place. Its interpretation and its consequences have inspired continued research efforts for almost a century. In its modern formulation, the uncertainty relation is understood as setting a fundamental bound on how fast any quantum system can evolve. In this Colloquium we will discuss important milestones,

Continue reading… Sebastian Deffner (Univ Maryland Baltimore County)

IMAGING PHYSICS SEMINAR

Katy Keenan
Applied Physics Division, Physical Measurement Lab
National Institute of Standards and Technology

Quantitative MRI for Precision Medicine

The ability of MRI to measure real, physical parameters of interest requires reference standards to ensure accuracy and reproducibility of data. Currently, variability exists across MRI systems, manufacturers, models, software versions, and analysis packages, which impedes comparison of data across patients, centers, and time. To move towards precision medicine, we must be able to determine the threshold of normal compared to disease state with a diagnostically useful uncertainty.

Continue reading… Katy Keenan Applied Physics Division, Physical Measurement Lab National Institute of Standards and Technology Quantitative MRI for Precision Medicine

IMAGING PHYSICS SEMINAR
Debra McGivney
Research Scientist, Department of Radiology
Case Western Reserve University

Inverse Problems in Medical Imaging

Mathematical inverse problems are used to model a wide variety of practical problems, including problems in medical imaging. Here, the unknown of interest is an image of the inside of the human body, which is not directly observable, but must be reconstructed given measurements made outside of the body. Oftentimes, reconstruction problems in imaging are ill-posed, which can result in errors in the reconstructed solution. Medical imaging plays a vital role in the diagnosis,

Continue reading… Debra McGivney, Dept. Radiology CWRU, Inverse Problems in Medical Imaging

Unification from Scattering Amplitudes
 
The modern S-matrix program offers an elegant approach to bootstrapping quantum field theories without the aid of an action.  While most progress has centered on gravity and gauge theory, similar ideas apply to effective field theories (EFTs).  Sans reference to symmetry or symmetry breaking, we show how certain EFTs can be derived directly from the properties of the tree-level S-matrix, carving out a theory space of consistent EFTs from first principles.  Furthermore, we argue that the S-matrix encodes a hidden unification of gravity, gauge theory, and EFTs.  In particular, starting from the tree-level S-matrix of the mother of all theories,

Continue reading… Cliff Cheung (Caltech)

Tunable Surface States of Topological Materials

Yuan-Ming Lu, The Ohio State University

The discovery of topological insulators revealed a large class of topological materials, which exhibit novel surface states with unusual properties. I will discuss some recent progress in engineering surface states of topological materials, focusing on two different systems. The 1st class of materials is three-dimensional Dirac semimetals including Na3Bi and Cd3As2, whose topological surface states can be deformed in these materials by either doping or applying mechanical strain. The 2nd class of materials are spin-orbit coupled quantum magnets, which can host topological magnon surface states robust again disorders.

Continue reading… Yuan-Ming Lu, The Ohio State University, Tunable Surface States of Topological Materials

IMAGING PHYSICS SEMINAR
Alexey Tonyushkin
University of Massachusetts Boston
Breaking the Rules in Magnetic Particle Imaging
and Ultra-High Field MRI

Magnetic Particle Imaging (MPI) is a new tomographic imaging modality that offers high spatial and temporal resolution. Compared to the other imaging modalities such as MRI/CT/PET, MPI is non-toxic, more sensitive, and fully quantitative technique. To date a few small-bore MPI systems were developed, however, human-size MPI scanner has yet to be built. The major challenge of scaling up of MPI is in high power consumption that is associated with the traditional approach to designing the scanner.

Continue reading… Alexey Tonyushkin University of Massachusetts Boston, Breaking the Rules in Magnetic Particle Imaging and Ultra-High Field MRI

Continue reading… Spring Break

IMAGING PHYSICS SEMINAR
Michael Boss
National Institute of Standards and Technology
Quantitative MRI: from Bench to Bedside

Quantitative MRI: from Bench to Bedside Magnetic Resonance Imaging (MRI) is an exquisite tool for probing the anatomical structure of the human body. It is also capable of measuring physical parameters such as relaxation times, diffusion and temperature, known as quantitative imaging biomarkers (QIBs). When acquired using methods with known limits of bias and reproducibility, these QIBs allow for comparison of scan data across patients, imaging sites, and time, turning into a powerful tool for clinical trials and patient care to evaluate disease state and treatment response.

Continue reading… Michael Boss, NIST, Quantitative MRI: from Bench to Bedside

Continue reading… Spring break ( no seminar)

Continue reading… APS March Meeting

A New Era for Solar Neutrinos
Abstract: Studies of solar neutrinos have been tremendously important, revealing the nature of the Sun’s power source and that its neutrino flux is strongly affected by flavor mixing.  Nowadays, one gets the impression that this field is over.  However, this is not due to a lack of interesting questions; it is due to a lack of experimental progress.  I show how this can be solved, opening opportunities for discoveries in particle physics and astrophysics, simultaneously.

Continue reading… John Beacom (The Ohio State University)

Continue reading… APS March Meeting ( no seminars)

First Results from CUORE: 

Majorana Neutrinos and the Search for Neutrinoless Double-Beta Decay

The neutrino is unique among the Standard Model particles. It is the only fundamental fermion that could be its own antiparticle, a Majorana particle. A Majorana neutrino would acquire mass in a fundamentally different way than the other particles and this would have profound consequences to particle physics and cosmology. The only feasible experiments to determine the Majorana nature of the neutrino are searches for the rare nuclear process neutrinoless double-beta decay. CUORE uses tellurium dioxide crystals cooled to 10 mK to search for this rare process.

Continue reading… Lindley Winslow (MIT)

First Results from CUORE: Majorana Neutrinos and the Search for Neutrinoless Double-Beta Decay
The neutrino is unique among the Standard Model particles. It is the only
fundamental fermion that could be its own antiparticle, a Majorana particle. A
Majorana neutrino would acquire mass in a fundamentally different way than the
other particles and this would have profound consequences to particle physics and
cosmology. The only feasible experiments to determine the Majorana nature of the
neutrino are searches for the rare nuclear process neutrinoless double-beta decay.
CUORE uses tellurium dioxide crystals cooled to 10 mK to search for this rare
process.

Continue reading… Lindley Winslow (MIT)

Shuhao Liu:  A Temperature Driven Hole-phonon Coupling Enhancement Effect in a Strongly Correlated 2D Hole System.

Kasun V. M. N. G. Premasiri:  Tuning Rashba Spin-orbit Coupling in Few-layer InSe.

Kyle Crowley: Doping and Field Effect in Novel 2D Layered Oxides

Santosh Kumar Radha: Distortion modes in inorganic halide perovskites: to twist or to stretch.

Narasak Pandech: First-principles Investigation of The Role of Organic Molecules Inside The α-phase of Hybrid Halide Perovskite CH3NH3BX3 (B= Pb,

Continue reading… APS March Meeting preview: student practice talks

Separating the role of chromatin from lamins in mechanics and morphology of the cell nucleus

Andrew Stephens, Northwestern U.

The nucleus is the 10 µm ellipse compartment in the cell which must properly transduce or resist biophysical
forces to dictate the spatial organization of the 2 meters of genome inside of it. Organization and
mechanotransduction determine the expression profile of genome which dictates cell function. Previous studies
revealed that the two major contributors to nuclear mechanics are lamins, protein intermediate filaments lining
the inner nuclear envelope, and chromatin, the DNA genome and its associated proteins,

Continue reading… Andrew Stephens, Northwestern U., Separating the role of chromatin from lamins in mechanics and morphology of the cell nucleus

Left-Right Symmetry: At the Edges of Phase Space and Beyond

The Left-Right Symmetric model (LRSM) remains one of the best motivated completions of the Standard Model of Particle Physics. Thus far, however, data from the CERN Large Hadron Collider (LHC) tell us that new particles, if they are still accessible, must be very heavy and/or very weakly coupled. Interestingly, these regions of parameter space correspond to collider signatures that are qualitatively and quantitatively different from those developed in pre-LHC times. We present several new LRSM collider signatures for these parameter spaces and show a greatly expanded discovery potential at the 13 TeV LHC and hypothetical future 100 TeV very large hadron collider.

Continue reading… Richard Ruiz (IPPP-Durham, UK)

Proteins in nanoporous hydrogels: adsorption, diffusion, and folding

Lydia Kisley

Beckman Institute, University of Illinois at Urbana-Champaign

Abstract:  Proteins within nanoporous hydrogels have important biotechnological applications in
pharmaceutical purification, tissue engineering, water treatment, biosensors, and medical
implants. Yet, oftentimes proteins that are functional in solution lose activity when in contact
with soft nanostructured materials due to perturbations in the folded state, conformation,
diffusion, and adsorption dynamics of the protein by the material. We have developed several
unique nanoscale fluorescent spectroscopies to image the heterogeneity of protein dynamics
within hydrogels.

Continue reading… Lydia Kisley, Univ. Illinois at Urbana-Champaign, Proteins in nanoporous hydrogels: adsorption, diffusion, and folding

No seminar physics fac. meeting

Continue reading… Fac. meeting

Mysteries of the quantum Hall staircase

Quantum Hall effects are a very rich subject in condensed matter physics with many connections to other areas, intrinsic intellectual beauty, and numerous applications. After more than 35 years after the initial discovery, there are new surprising and unexpected phenomena being discovered in this area, both in experiments and in theory. A visual manifestation of the effects is the plot of the Hall resistance as a function of magnetic field, featuring prominent, precisely quantized steps, also called plateaux, and thereby resembling a staircase. The walk up this staircase is a journey in time,

Continue reading… Ilya Gruzberg (Ohio State University)

Testing baryons from bubbles with colliders and cosmology  
“Why is there more matter than antimatter?”  This simple question is arguably the most longstanding and challenging problem in modern cosmology, but with input from the next generation of particle physics experiments we may finally have an answer!  In the talk I will discuss how precision measurements of the Higgs boson at the LHC and future high energy collider experiments will be used to test the idea that the matter-antimatter asymmetry arose during the electroweak phase transition in the fractions of a second after the big bang.  Other cosmological phase transitions can also provide the right environment for generating the matter excess. 

Continue reading… Andrew J. Long (Kavli Institute for Cosmological Physics, University of Chicago)

Harsh Mathur (Physics) on the prize in Physics; Phoebe Stewart (Pharmacology) on the prize in Chemistry; Peter Harte (Genetics and Genome Sciences) on the prize in Physiology or Medicine; Mariana Carrera (Weatherhead) on the prize in Economics. 

On 14 September 2015 the LIGO collaboration detected gravitational waves from the merger of a pair of black holes a billion light years distant from the Earth. The discovery constitutes the first direct observation of gravitational waves almost a century after they were predicted by Einstein and is the culmination of a fifty year long experimental quest. LIGO is simultaneously a laboratory for fundamental gravitational physics and an observatory of a new kind that promises to revolutionize astronomy.

Continue reading… The 2017 Nobel Prizes: What were they given for?

Radiative Corrections in Universal Extra Dimensions

Universal extra dimensions is an interesting extension of the Standard Model
that is naturally protected from electroweak precision constraints and provides
a natural dark matter candidate. Its phenomenology at the LHC is strongly
affected by radiative corrections. On one hand, QCD corrections are important
for understanding the production of heavy gluons and quarks, which are the
particles with the largest production rates at the LHC. On the other hand,
radiative corrections crucially modify the mass spectrum and interactions of the
heavy resonances. This talk will describe recent progress on both of these
fronts.

Continue reading… Ayres Freitas (University of Pittsburgh)

Neutrino Portal Dark Matter

Dark matter that interacts with the standard model (SM) through the “neutrino portal” is a possibility that is relatively less well studied than other scenarios. In such a setup, the dark matter communicates with the SM primarily through its interactions with neutrinos. In this talk, I will motivate neutrino portal dark matter and discuss some new tests of this possibility.

Continue reading… David McKeen (University of Pittsburgh)

Spins & Knots: The rise of Topology in f-orbital materials

Maxim Dzero

Kent State University

In my talk I will review the key recent theoretical and experimental works on a new class of topological material systems – topological Kondo insulators, which appear as a result of interplay between strong correlations and spin-orbit interactions. I will discuss the history of Kondo insulators is along with the theoretical models used to describe these heavy fermion compounds. The Fu-Kane method of topological classification of insulators is used to show that hybridization between the conduction electrons and localized f-electrons in these systems gives rise to interaction- induced topological insulating behavior.

Continue reading… Maxim Dzero, Kent State University, Spins & Knots: The rise of Topology in f-orbital materials

Tunneling in Quantum Field Theory and the Ultimate Fate of our Universe

One of the most concrete implications of the discovery of the Higgs boson is that, in the absence of physics beyond the standard model, the long-term fate of our universe can now be established through precision calculations. Are we in a metastable minimum of the Higgs potential or the true minimum? If we are in a metastable vacuum, what is its lifetime? To answer these questions, we need to understand tunneling in quantum field theory.This talk will give an overview of the interesting history of tunneling rate calculations and all of its complications in calculating functional determinants of fluctuations around the bounce solutions.

Continue reading… Anders Johan Andreassen (Harvard University)

Prof. Dr. Elshad Allahyarov, 

Duisburg-Essen University, Germany, and  Physics Department  CWRU

Smectic monolayer confined on a sphere: topology at the particle scale

The impact of topology on the structure of a smectic monolayer confined to a sphere is explored by particle-resolved computer simulations of hard rods. The orientations of the particles are either free or restricted to a prescribed director field with a latitude or longitude orderings. Depending on the imprinted topology, a wealth of different states are found including equatorial smectic with isotropic poles, equatorial smectic with empty poles,

Continue reading… Elshad Allahyarov, Duisburg-Essen University and CWRU, Smectic monolayer confined on a sphere: topology at the particle scale

On Ising’s model of ferromagnetism

The 1D Ising model is a classical model of great historical significance for both classical and quantum statistical mechanics. Developments in the understanding of the Ising model have fundamentally impacted our knowledge of thermodynamics, critical phenomena, magnetism, conformal quantum field theories, particle physics, and emergence in many-body systems. Despite the theoretical impact of the Ising model there have been very few good 1D realizations of it in actual real material systems. However, it has been pointed out recently, that the material CoNb2O6, has a number of features that may make it the most ideal realization we have of the Ising model in one dimension.  

Continue reading… Peter Armitage (Johns Hopkins)

title and abstract tba

Continue reading… Dragan Huterer (U. Michigan)

New Views of the Universe

I will discuss how progress in cosmology over the past decade has improved our understanding of dark matter, dark energy, and the physics of the early universe. I will particularly concentrate on the developments in mapping out the expansion rate of the universe and the growth of density fluctuations in order to better understand dark energy and, eventually, identify the physics responsible for universe’s accelerated expansion.  The talk will provide basic background and discuss exciting new developments at a level accessible to graduate students.

Continue reading… Dragan Huterer (Univ Michigan)

Prof. Samo Kralj

University of Maribor, Maribor & Jožef Stefan Institute, Ljubljana, Slovenia

 Impact of intrinsic and extrinsic curvature on membrane shapes

Red blood cells (erythrocytes) are present in almost all vertebrates and their main function is the transport of oxygen to the body tissues. Their shape dominantly influences their functionality. In almost all mammals in normal conditions erythrocytes adopt a disk-like (discocyte) shape which optimizes their flow properties in large vessels and capillaries. Experimentally measured values  of  the  relative volume v of stable discocyte shapes  range in a relatively broad window.

Continue reading… Samo Kralj, University of Maribor, Impact of intrinsic and extrinsic curvature on membrane shapes

title and abstract tba

Continue reading… Arthur Kosowsky (Pittsburgh)

Continue reading… No seminar, Faculty meeting

Positron Annihilation Spectroscopy and Measurements of Origin of Novel Electronic Phenomena in Semiconductors and Oxides    

Farida A. Selim, Department of Physics and Astronomy, Bowling Green State University  

Center for Photochemical Sciences, Bowling Green State University

 Positron Annihilation Spectroscopy (PAS) has been established as an effective tool to probe electron states and measure atomic scale defects in solids. However, when combined with other techniques, PAS becomes also a powerful tool for revealing and explaining many interesting electronic phenomena. In our laboratory, we combined PAS with structural and transport measurements as well as with infrared,

Continue reading… Farida Selim, Bowling Green State University, Positron Annihilation Spectroscopy and Measurements of Origin of Novel Electronic Phenomena in Semiconductors and Oxides

Mechanism of Aluminum-Oxide Scale Formation on some High-Temperature Structural Alloys

The formation of Al2O3 scale on high-temperature structural alloys is a subject of immense technological importance, as well as of considerable scientific interest. Contrary to much current thinking in the field, the kinetics of scale growth appear to be controlled by the electrical conductivity of the scales, rather than solely by the diffusion of aluminum and oxygen at grain boundaries. Considerations of band structure thus become of major importance. The atomic structures and the electronic density of states were computed for a group of bi-crystal boundaries using density-functional theory.

Continue reading… A.H. Heuer (CWRU Materials Science and Engineering)

Cosmology with ACTPol and AdvACT

The bolometric polarimeter at the focal plane of the Atacama Cosmology Telescope allows us to map the Cosmic Microwave Background (CMB) with high signal-to-noise both in temperature and polarization.  In this talk, I will present the data-reduction pipeline, highlighting the importance of making maximum-likelihood unbiased CMB maps. I will show the two-season ACTPol cosmological results presented in Louis et al. (2017), Sherwin et al. (2017), and Hilton et al. (2017) and describe the current effort to finalize the analysis of the ACTPol dataset. I will conclude with preliminary results from the ongoing AdvACT survey,

Continue reading… Simone Aiola (Princeton)

A New Kind of Magnetism – The Dzyaloshinskii-Moriya Interaction

Vincent Sokalski, Dept. of Materials Science and Engineering, Carnegie Mellon University

Magnetism has had a profound effect on our everyday lives from compass needles in ancient times to the modern hard disc drive in today’s computers.  The existence of magnetic materials is rooted in the Heisenberg exchange interaction energy, , which favors parallel (or anti-parallel) alignment of neighboring spin vectors and their associated magnetic dipole moments as found, for example, in Fe, Ni, and Co.  In the past decade a different type of magnetic exchange came to the forefront of modern physics called the Dzyaloshinskii-Moriya Interaction (DMI) given by ,

Continue reading… Vincent Sokalski, Carnegie Mellon University, A New Kind of Magnetism – The Dzyaloshinskii-Moriya Interaction

2D Materials: from Semiconductors to Topological Insulators

Abstract: Since the first isolation of one-atom thick graphene, research on two-dimensional (2D) materials with layered crystal structure has exploded over the past decade. One focal point in the recent studies of 2D materials beyond graphene is the development of metal chalcogenides (e.g. MoS2) as 2D semiconductors. In this talk, I will first highlight our exploration of non-transition metal chalcogenides InSe and SnS for future 2D semiconductor applications. While multilayer InSe is demonstrated to be a promising new 2D semiconductor for high performance n-type transistor devices, SnS’s intrinsic p-type nature leads to both opportunities and challenges in p-type semiconductor device applications.

Continue reading… Xuan Gao (CWRU Physics)

Spin, Charge and Heat Transport in Low-Dimensional Materials

Chun Ning (Jeanie) Lau

Department of Physics, The Ohio State University, Columbus, OH 43210, USA

Low dimensional materials constitute an exciting and unusually tunable platform for investigation of both fundamental phenomena and electronic applications. Here I will present our results on transport measurements of high quality few-layer phosphorene devices, and the unprecedented current carrying capacity of carbon nanotube “hot dogs”. In the second half of the talk, I will present our recent observation of robust long distance spin transport through the antiferromagnetic state in graphene.

Continue reading… Jeanie Lau, The Ohio State University, Spin, Charge and Heat Transport in Low-Dimensional Materials

Title: Amplitudes for massive spinning particles
 Abstract: I will review a method for constructing scattering amplitudes for spinning particles and then discuss how these amplitudes can be used to constrain massive gravity and theories containing higher-spin particles.

Continue reading… James Bonifacio (Oxford and CWRU)

Gelation of Particles with Short-ranged Attraction

Nanoscale or colloidal particles are exceptionally important in many realms of science and technology. They can dramatically change the properties of materials, imparting solid-like behavior to a wide variety of complex fluids, from yoghurt to cast ceramics. This behavior arises when particles aggregate to form mesoscopic clusters and networks. The essential component leading to aggregation is an interparticle attraction, which can be generated by many physical and chemical mechanisms. In the limit of irreversible aggregation, infinitely strong interparticle bonds lead to diffusion-limited cluster aggregation (DLCA), long-understood as a purely kinetic phenomenon,

Continue reading… Peter Lu (Harvard University)

Lecture co-sponsored by the departments of Physics and Art History, the Baker-Nord Center for the Humanities, and the Cleveland Museum of Art. Note unusual time and venue.

The conventional view holds that geometric star-and-polygon patterns in medieval Islamic architecture were designed using a straightedge and a compass. Peter Lu, a research associate at Harvard University, will present his findings that, instead, a wide variety of patterns with five- and ten-fold symmetry were conceived as tessellations of specific decorated puzzles pieces, called girih tiles, that appear in medieval Islamic architectural scrolls. Beginning in the 12th century, patterns designed with these girih tiles appeared throughout the Islamic world,

Continue reading… Peter Lu (Harvard University) (Not a Colloquium but of related interest)

Majorana Materializes 

In 1937 Ettore Majorana introduced the concept of what are now fittingly called Majorana fermions — fermionic particles that are their own antiparticles. Nowadays an active search for condensed-matter analogues of these elusive objects is well underway, motivated by both the prospect of revealing new facets of quantum mechanics and longer-term quantum computing applications. This talk will survey recent advances in this pursuit. In particular, I will describe strategies for “engineering” Majorana platforms from simple building blocks, preliminary experimental successes, and future milestones that reveal foundational aspects of Majorana physics directly relevant for quantum computation.

Continue reading… Jason Alicea (Caltech)

The Standard Cosmological Model: A Status Report

Overall, the standard cosmological model has enjoyed enormous empirical success. But there are  a number of indicators that we might be missing something. These include the large-scale cosmic microwave background (CMB) “anomalies”, and two to three sigma discrepancies between cosmological parameters derived from larger angular scales of the CMB vs. smaller angular scales, CMB lensing potential reconstruction vs. CMB power spectra, data from the Planck satellite vs. data from the South Pole Telescope, and CMB-calibrated predictions for  the current rate of expansion vs. more direct measurements. I will introduce the standard cosmological model,

Continue reading… Lloyd Knox (UC Davis)

Opto-electronic studies of novel self-contacted 2D materials based devices

Eric Stinaff

Department of Physics and Astronomy, Ohio University

Interest in two-dimensional crystals has grown exponentially over the last decade, a testament to their vast technological and scientific potential. In addition to properties such as high mobilities, semiconducting and superconducting behavior, and excellent thermal properties, many of these materials have the potential for novel opto-electronic applications, with large absorption, strong room-temperature emission, non-linear response, and optical control of spin and valley degrees of freedom. In this presentation, we will discuss an experimental investigation of mono-to-few-layer sheets of MoS2 and WS2 employing femtosecond transient absorption spectroscopy (FTAS) and microscopy.

Continue reading… Eric Stinaff, Ohio University, Opto-electronic studies of novel self-contacted 2D materials based devices

Continue reading… No colloquium this week

Title: The Surprisingly Complex Lives of Massive Galaxies
 
Abstract: Massive galaxies reside in the densest and most evolved regions of the Universe, yet we are only beginning to understand their formation history. Once thought to be relics of a much earlier epoch, the most massive local galaxies are red and dead ellipticals, with little ongoing star formation or organized rotation. In the last decade, observations of their assumed progenitors have demonstrated that the evolutionary histories of massive galaxies have been far from static. Instead, billions of years ago, massive galaxies were morphologically different: compact, possibly with more disk-like structures,

Continue reading… Rachel Bezanson (Pittsburgh)

X-ray Experiments in Liquid Crystal Science and Technology

Michael Fisch

Kent State University

The use of X-rays to study liquid crystals has a long history, and is still of continuing interest.  A brief review of liquid crystals and X-ray diffraction from common liquid crystalline phases will be presented.  Interpretation of the resulting diffraction patterns will be discussed, and some of our current experiments in bent-core molecules and “organic salts will be discussed.  The relationship of these studies to current problems in liquid crystal science and technology will be briefly explored,

Continue reading… Michael Fisch, Kent State University, X-ray Experiments in Liquid Crystal Science and Technology

Pure & Poetic: Butterfly in the Quantum World

The Hofstadter butterfly is a fascinating two-dimensional spectral landscape – a graph of the allowed energies of an electron in a two-dimensional crystal in a magnetic field. It is a quantum fractal made up of integers, describing topological states of matter known as the integer quantum Hall states. My butterfly story tells the tale of its discovery by a graduate student named Douglas Hofstadter and discusses its number theoretical, geometrical and topological aspects [1]. I will describe how the integers of the butterfly are convoluted in the Pythagorean triplets and the integer curvature of Apollonian gaskets,

Continue reading… Indu Satija (George Mason University)

Continue reading… No seminar, faculty meeting

Galaxy Clustering and the Galaxy-Halo Connection

In the contemporary view of the Universe, galaxies form and evolve in dark matter halos.  Modern galaxy surveys, most notably the Sloan Digital Sky Survey, have transformed the study of large-scale structure enabling detailed measurements of the spatial distribution of galaxies. I will discuss how we interpret these measurements using contemporary models of galaxy clustering which elucidate the relation between galaxies and dark matter halos. I will further describe one of the main challenges currently facing such analyses and present new results for the dependence of the galaxy content of halos on the assembly history of their host halos.

Continue reading… Idit Zehavi (CWRU, Astronomy)

The next massive galaxy and quasar frontier at the Cosmic Dawn

Many of the advances in our understanding of cosmic structure have come
from direct computer modeling. In cosmology, we need to develop computer
simulations that cover this vast dynamic range of spatial and time
scales. I will discuss recent progress in cosmological hydrodynamic
simulations of galaxy formation at unprecedented volumes and
resolution. I will focus on predictions for the first quasars and
their host galaxies in the BlueTides simulation.  BlueTides is a
uniquely large volume and high resolution simulation of the high
redshift universe: with 0.7 trillion particles in a volume half a
gigaparsec on a side.

Continue reading… Tiziana Di Matteo (Carnegie Mellon)

Automatic search versus chemical rules in materials structure study
Maosheng Miao
Department of Chemistry and Biochemistry, California State University Northridge CA,
USA; Beijing Computational Science Research Center, Beijing, China

The increase of the computer power in the past decades not only allow us to calculate
larger systems with higher accuracy in materials studies, but also provide the opportunity
to explore large configuration spaces such as structures and compositions. Automatic
structure searches have been very successful in predicting structures of bulk materials. It
seems out of question whether the automatic search is advantageous over traditional
structure design based on chemical knowledge and intuition.

Continue reading… Maosheng Miao, California State University Northridge, Automatic search versus chemical rules in materials structure study

Correlated Nanoelectronics 

The study of strongly correlated electronic systems and the development of quantum transport in nanoelectronic devices have followed distinct, mostly non-overlapping paths.  Electronic correlations of complex materials lead to emergent properties such as superconductivity, magnetism, and Mott insulator phases.  Nanoelectronics generally starts with far simpler materials (e.g., carbon-based or semiconductors) and derives functionality from doping and spatial confinement to two or fewer spatial dimensions.  In the last decade, these two fields have begun to overlap.  The development of new growth techniques for complex oxides have enabled new families of heterostructures which can be electrostatically gated between insulating,

Continue reading… Jeremy Levy (Univ Pittsburgh)

Neutrinos: cool, cold, coldest
 
In all of particle physics, neutrinos are some of the most ghostly particles we’ve detected. While the story of their discovery was pretty cool in itself, some modern experiments are even cooler. 
 
The IceCube experiment, located at the geographic South Pole, was originally designed to collect astro-particle data, especially by looking for neutrino point sources as potential sources of the highest energy cosmic rays. But because of its immense fiducial volume, IceCube can collect high-statistic neutrino data, and thus measure oscillation parameters with precision that rivals dedicated oscillation experiments. 
 
The CUORE experiment examines majorana nature of neutrinos by looking for neutrinoless double beta decay in the coldest cubic meter in the Universe,

Continue reading… Laura Gladstone (CWRU)

Antiferromagnetic resonance and in-gap terahertz continuum in Kitaev Honeycone magnet α−RuCl3

Spin-1/2 moments in the antiferromagnetic Mott insulator α-RuCl3 are coupled by strongly anisotropic bond-dependent exchange interactions on a honeycomb lattice. Intense study of α- RuCl3 by inelastic scattering has been driven by the proposal that its low energy excitations may be adiabatically connected to the Majorana quasiparticles that emerge in the exact solution of the Kitaev spin liquid model. In my talk, I will present optical absorption measurements using time- domain terahertz spectroscopy in the range 0.3 to 10 meV that reveal several new features of the low-energy spectrum of α-RuCl3 [1].

Continue reading… Liang Wu, UC Berkeley, MPPL3, Antiferromagnetic resonance and in-gap terahertz continuum in Kitaev Honeycomb magnet α−RuCl3

Quantized electro-dynamical responses in topological materials

Although solid-state systems are usually considered “dirty” with impurities and imperfections, it is still the case that macroscopic, quantized phenomena can be observed in the form of the Josephson effect in superconductors and the quantum Hall effect in 2DEG. Combinations of these measurements allow you to determine Planck’s constant and the fundamental charge in a solid-state setting. In my talk, I will show you the observation of a new quantized response in units of the fine structure constant in a new class of material so called “topological insulators” (Tis). First,

Continue reading… Liang Wu (Berkeley); Michelson Postdoctoral Prize Lecture

Giant nonlinear optical responses in Weyl semimetals

Recently Weyl quasi-particles have been observed in transition metal monopnictides (TMMPs) such as TaAs, a class of noncentrosymmetric materials that heretofore received only limited attention. The question that arises now is whether these materials will exhibit novel, enhanced, or technologically applicable properties. The TMMPs are polar metals, a rare subset of inversion- breaking crystals that would allow spontaneous polarization, were it not screened by conduction electrons. Despite the absence of spontaneous polarization, polar metals can exhibit other signatures, most notably second-order nonlinear optical polarizability, leading to phenomena such as second-harmonic generation (SHG).

Continue reading… Liang Wu, University California Berkeley, MPPL2,Giant nonlinear optical responses in Weyl semimetals

Low-energy Electrodynamics of 3D Topological Insulators

Topological insulators (TIs) are a recently discovered state of matter characterized by an “inverted” band structure driven by strong spin-orbit coupling. One of their most touted properties is the existence of robust “topologically protected” surface states.  I will discuss what topological protection means for transport experiments and how it can be probed using the technique of time- domain THz spectroscopy applied to 3D TI thin films of Bi2Se3.  By measuring the low frequency optical response, we can follow their transport lifetimes as we drive these materials via chemical substitution through a quantum phase transition into a topologically trivial regime [1].

Continue reading… Liang Wu, University California Berkeley, MPPL1, Low-energy Electrodynamics of 3D Topological Insulators

History, Geometry and the Future of Mobility

For over a century the personal automobile has served as a highly adaptable transportation tool and an aspirational symbol of wealth and freedom.  However, two megatrends would appear to spell its doom:  climate change with the recognition of the need to reduce CO2 emissions, and urbanization with the unprecedented size and density of new emerging megacities where significant vehicle ownership would result in ‘total gridlock’.  Surprisingly, both of these are actually questions of geometry – and a little physics – informed by the history of cities in the developed world. 

Continue reading… Mike Tamor (Ford Research)

title and abstract tba

Continue reading… Gabriela Marques, National Observatory of Rio de Janeiro and CWRU

Quantum valley Hall kink states and valleytronics in bilayer graphene

Conventional field effect transistors control current transmission by controlling the charge of carriers. The advent of two-dimensional materials with hexagonal crystal symmetry offers a new electronic degree of freedom, namely valley, the manipulation and detection of which could potentially be exploited to form new many-body ground states as well as new paradigms of electronic applications. In this talk, I will describe our work in creating valley-momentum locked quantum wires, namely quantum valley Hall kink states, in Bernal stacked bilayer graphene and show the operations of a waveguide,

Continue reading… Jun Zhu (Penn State)

Jie Gao

Missouri University of Science and Technology (University of Missouri – Rolla)

Tailoring light-matter interaction with metamaterials and metasurfaces

Metamaterials and metasurfaces with designed subwavelength nanostructures exhibit intriguing electromagnetic phenomena, such as negative refraction, invisible cloaking, sub-diffraction imaging, near-zero permittivity and hyperbolic dispersion. In this talk, I will present our recent work on tailoring light-matter interaction with metamaterials and metasurfaces, including the realization of enhanced spontaneous emission, ultrasensitive molecule detection, strong plasmon-phonon interaction, optical vortex generation and full-color metasurface hologram. These results present opportunities and challenges in understanding new physics of light-matter interaction in those artificially structured optical materials and realizing many unprecedented applications in nanophotonics.

Continue reading… Condensed Matter Seminar: Jie Gao, Missouri University of Science and Technology (University of Missouri – Rolla)

Cosmological open quantum systems

Our current understanding of the universe relies on an inherently quantum origin for the rich, inhomogeneous structure we see today. Inflation (or any of the alternative proposals for the primordial era) easily generates a universe exponentially larger than what we can observe. In other words, the modes that are observationally accessible make up an open quantum system. I will discuss what we might learn by thinking about the universe in this way, even though the quantum structure is probably not observable.

Continue reading… Sarah Shandera (Penn State)

Planets Around Nearby Stars

Modern science began with Copernicus speculating that the Earth is a
planet and that all the planets orbit the Sun.  Bruno followed up by
speculating that the Sun is a star, that other stars have planets, and
other planets are inhabited by life.  For this and other heresies,
Bruno was burned at the stake in a public square in Rome in 1600.
Astronomy and extrasolar planets were a really hot field at the time.

Over the past 20 years more than a thousand extrasolar planets have
been found,

Continue reading… Paul Butler (Carnegie Institute of Washington)

Primordial gravitational waves: Imprints and search

Discussed will be some interesting scenarios for the generation of gravitational waves from inflation and the characteristic imprints we can search with upcoming cosmological observations.

Continue reading… Ema Dimastrogiovanni (CWRU)

CANCELED. Will be rescheduled.

Simulate to discover: from new chemistry under high pressure to novel two-dimensional materials

Maosheng Miao

Department of Chemistry and Biochemistry

California State University Northridge, California 91330, USA

The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry, rooted in the atomic shell structure. Within compounds, Group I elements, for example, invariably assume the +1 oxidation state, and their chemical properties differ completely from those of the p-block elements.

Continue reading… CANCELED: Maosheng Miao, California State University Northridge,Simulate to discover: from new chemistry under high pressure to novel two-dimensional materials

Nanoparticles in liquid crystals, and liquid crystals in nanoparticles.
 
Liquid crystals are remarkably sensitive to interfacial interactions. Small perturbations at a liquid crystal interface can in fact be amplified over relative long distances, thereby providing the basis for a wide range of applications. Our recent research efforts have focused on the reverse phenomenon; that is, we have sought to manipulate the interfacial assembly of nanoparticles or the organization of surface active molecules by controlling the structure of a liquid crystal. This presentation will consist of a review of the basic principles that are responsible for liquid crystal-mediated interactions,

Continue reading… Juan de Pablo (University of Chicago)

The Fast and the Furious: Energetic Ion Transport in Magnetic Fusion Devices

D.C. Pace and the DIII-D National Fusion Facility Team

General Atomics, P.O. Box 85608, San Diego, CA 92186-5608, USA

David Pace

Nuclear fusion has the potential to be an energy source that powers society without generating greenhouse gases or high-level radioactive waste. The tokamak approach to controlled nuclear fusion employs a toroidally-shaped magnetic field configuration to confine plasmas at temperatures beyond 200 million K (20 keV). Future reactors aim to utilize the deuterium-tritium fusion reaction due to its favorable cross-section,

Continue reading… David Pace, General Atomics, San Diego, The Fast and the Furious: Energetic Ion Transport in Magnetic Fusion Devices

Mapping Ultra Large Scale Structure

Anomalies in the CMB on large angular scales could find an explanation in terms of pre-inflationary physics or intrinsic statistical anisotropies. However, due to cosmic variance it is difficult to conclusively test many of these ideas using the primary cosmic microwave background (CMB) alone. In this talk, I will outline a program to place stringent observational constraints on theories that predict ultra-large scale structure or statistical anisotropies using the secondary CMB (the Sunyaev Zel’dovich effect, polarization form the post-reionization era, lensing, etc.) and tracers of large-scale structure. These methods will become accessible with next-generation CMB experiments and planned galaxy surveys.

Continue reading… Matthew Johnson (Perimeter Institute)

Shining new light on old problems in lithium ion batteries

Louis Piper

Binghamton University, State University of New York

Improving the energy storage and release of lithium ion battery is largely limited to the cathode (positive electrode).  Commercial high capacity LIBs employ Ni-rich layered oxides (derived from LiCoO2) as cathodes.  In these systems, the reversible energy storage capacity is limited to 1 Li+ per transition metal (i.e. Co3+/4+ redox couple).  However, only 2/3 of Li+ per redox couple are typically intercalated due to capacity retention issues with fast cycling and high voltages. 

Continue reading… Louis F. Piper, Binghamton University, Shining new light on old problems in lithium ion batteries

Active Brownian particles: From individual to collective behavior

Single self-propelled particles as well as ensembles of self-propelled particles are examples of non-equilibrium states and a topic of the interdisciplinary research at the borderline between physics and biology. Interesting examples of self-moving objects come from biology, these are bacteria, eukaryots, amoeba, insects, fishes and animals etc. But also in physics self-moving objects are known, which are active colloids and moving spots in reaction-diffusion systems.

I will review various models of self-propelled particles from a viewpoint of statistical physics. Special attention is payed to the influence of noise on the dynamics of single particles and on the exhibition of spatial structures in groups of interacting moving particles.

Continue reading… Lutz Schimansky-Geier (Humboldt University at Berlin)

The Cosmology Large Angular Scale Surveyor (CLASS)

Precise observations of the cosmic microwave background have played a leading role in the development of the LCDM model of cosmology, which has been successful in describing the universe’s energy content and evolution using a mere six parameters. With this progress have come hints that the universe underwent an inflationary epoch during its infancy.  Cosmic inflation is predicted to produce a background of gravitational waves that would imprint a distinct polarized pattern on the cosmic microwave background (CMB). Measurement of this polarized signal would provide the first direct evidence for inflation and would provide a means to study physics at energy scales around the predicted GUT scale. 

Continue reading… David Chuss (Villanova)

Novel magnetic phases in spin-orbit coupled oxides
Nandini Trivedi,
 
Department of Physics, The Ohio State University
 

Abstract: I will discuss puzzles about magnetism in some of the simplest oxide materials with a single electron in the d-orbital.  Starting from a microscopic model of a Mott insulator with both spins and orbitals, I will obtain the effective magnetic Hamiltonian and provide insights into the experimental puzzles. 

Continue reading… Nandini Trivedi, The Ohio State University, Novel magnetic phases in spin-orbit coupled oxides

Active Matter: from colloids to living cells

Collections of self-propelled entities, from living cells to engineered microswimmers, organize in a rich variety of active fluid and solid states, with unusual properties. For instance, active fluids can flow with no externally applied driving forces and active gases do not fill their container. In this talk I will describe the behavior of such “active materials”, focusing on two examples of liquid-solid transitions driven by active processes. The first is the formation of cohesive matter with no cohesive forces in collections of purely repulsive active colloids. The second describes the properties of epithelial tissues that exhibit a liquid-solid transition at constant density driven by cell motility,

Continue reading… Cristina Marchetti (Syracuse)

Non-linearities in large-scale structure: Induced gravitational waves, non-linear galaxy bias

I will present my recent work on non-linearities in large-scale structures of the Universe. For the first part, I will discuss the gauge dependence of the scalar-induced tensor perturbations and its implication on searching the primordial gravitational wave signature from the large-scale structure. For the second part of the talk, I will give a brief overview of the recent review on large-scale galaxy bias (Desjacques, Jeong & Schmidt, 1611.09787) that contains a complete expression for the perturbative bias expansion that must hold on large scales.