College of Arts and Sciences

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)

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)

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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)

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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)

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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)

This talk will be rescheduled for another semester

Continue reading… Randall McEntaffer (Penn State University) POSTPONED

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)

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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)

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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)

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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)