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Qing Gu (NCSU): Materials Science and Engineering Seminar

Wu and Chen Auditorium (Levine Hall) 3330 Walnut Street, Philadelphia, PA, United States

Title: “Opportunities in Whispering-Gallery Microresonators: Fundamentals and Applications”

Dr. Gu received the Bachelor’s degree from University of British Columbia, Canada in 2008, and the Ph.D. degree from University of California, San Diego in 2014, both in Electrical Engineering. Prior to joining NC State, she was an Assistant Professor at the University of Texas at Dallas from 2016 to 2021. Her research activities include the experimental realization of quantum-inspired nanophotonic semiconductor light sources using emerging materials or novel cavity configurations, active and topological hyperbolic metamaterials, and perovskite optoelectronics. She is the author of book “Semiconductor Nanolasers” by Cambridge University Press, published in 2017.

Dr. Gu’s experimental research in nanophotonics lies at the intersection of electrical engineering, physics and materials sciences. She holds a joint appointment of ECE and Physics, and is a member of the Chancellor's Faculty Excellence Cluster in Carbon Electronics.

Doug Natelson (Rice University): Condensed and Living Matter Seminar

David Rittenhouse Lab A8 209 S 33rd St, Philadelphia, PA, United States

Title: “Shot noise as a probe of correlated materials / Light emission as a probe of electronic pDNrocesses at the nanoscale”

Strange metal behavior has been observed in materials ranging from high-temperature superconductors to heavy fermion metals. In conventional metals, current is carried by quasiparticles; although it has been suggested that quasiparticles are absent in strange metals, direct experimental evidence is challenging to acquire. We measure shot noise to probe the granularity of the current-carrying excitations in nanowires of the heavy fermion strange metal YbRh2Si2.

When compared to conventional metals, shot noise in these nanowires is strongly suppressed. We argue that this suppression can be attributed neither to electron-phonon nor to electron-electron interactions in a Fermi liquid, suggesting that the current is not carried by well-defined quasiparticles in the strange metal regime we probed.

This work sets the stage for similar studies of other strange metals, to test for universality of this response, and ideally for studies in single devices that may be tuned between Fermi liquid and strange metal regimes. It is also important to consider the noise in strongly interacting Fermi liquids, to see if interactions modify the expectations familiar from conventional mesoscopic physics. Time permitting, I will discuss some recent interesting findings in YbAl3, a mixed valence heavy fermion material.