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Physics Colloquium: Waseem Bakr, Probing dynamical properties of Fermi-Hubbard systems with a quantum gas microscope

Physics Colloquium: Waseem Bakr, Probing dynamical properties of Fermi-Hubbard systems with a quantum gas microscope
When Mar 27, 2019
from 04:00 PM to 05:00 PM
Contact Name
Contact Phone 212-650-7443
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Physics Colloquium

Probing dynamical properties of Fermi-Hubbard systems with a quantum gas microscope

 

Waseem Bakr

Associate Professor Department of Physics  Princeton University


The normal state of high-temperature superconductors exhibits anomalous transport and spectral properties that are poorly understood. Cold atoms in optical lattices have been used to realize the celebrated Fermi-Hubbard model, widely believed to capture the essential physics of these materials. The recent development of fermionic quantum gas microscopes has enabled studying Hubbard systems with single-site resolution. Most studies have focused on probing equal-time spin and density correlations. In this talk, I will report on using a microscope to probe response functions associated with unequal-time correlations relevant for understanding the pseudogap and strange metal regimes of Fermi-Hubbard systems. First, I will describe the development of a technique to measure microscopic diffusion, and hence resistivity, in doped Mott insulators. We have found that this resistivity exhibits a linear dependence on temperature and violates the Mott-Ioffe-Regel limit, two signatures of strange metallic behavior. Next, I will report on the development of angle-resolved photoemission spectroscopy (ARPES) for Hubbard systems and its application to studying pseudogap physics in an attractive Hubbard system across the BEC-BCS crossover, setting the stage for future studies of the pseudogap regime in repulsive Hubbard systems.

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Prof. Bakr's group’s research is focused on using ultracold quantum gases to explore the physics of strongly-correlated materials and to realize scalable architectures for quantum computation with optical lattices. Our experiments combine techniques from atomic physics, such as laser cooling and trapping, with ideas from condensed matter and quantum information.   My group is currently interested in exploring two broad areas of condensed matter physics with ultracold atomic gases: quantum magnetism and topological order. Our experiments on quantum magnetism will investigate spin systems where the interplay between competing interactions, geometric frustration and quantum fluctuations leads to novel magnetic phases.   Our studies of topological order will probe quantum states such as fractional quantum Hall states, topological insulators and topological superfluids that do not fit in Landau’s symmetry breaking scheme and cannot be characterized using local order parameters. Research