College of Arts and Sciences

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)

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

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?

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)

 
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)

Continue reading… No Colloquium. Spring Break.

Continue reading… No Colloquium. APS March Meeting.

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)

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)

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)

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)

“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)

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)