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Equilibrium and Quench-Dynamical Studies of Ultracold Fermions in Ring-Shaped Optical Traps

Daniel Allman, Dartmouth College
Wednesday, July 10, 2024 - 11:00am to 12:00pm
PAB B421

The unique capability to precisely tune the few and many-body configurations of ultracold Fermi gases provides a multi-faceted platform for studying novel, exotic aspects of quantum systems. These aspects include for instance superfluid/superconducting phenomena supported by potentially exotic pairing mechanisms, non-equilibrium and critical dynamics, and proposed quantum sensing or computing applications based on atomtronics. Ring geometries further provide natural arenas for probing (super)fluid transport and can offer platforms for extracting robust experimental signatures pertaining to complex many-body phenomena.

I will detail several key experimental results obtained from Dartmouth College's ultracold atoms lab, with a focus on ring-shaped ensembles of ultracold fermions. The first is a technical result that heating due to background molecular collisions can be substantially reduced by maintaining a reservoir of non-degenerate fermions in contact with a deeply-degenerate fermion ring. This finding, along with a convenient means of performing degenerate fermion thermometry, permits the possibility to perform experiments that require maintaining low temperatures to preserve fragile bound pairs for several seconds. The second result pertains to the spontaneous appearance of quantized currents following quenches across a superfluid phase transition. Findings shed light onto critical dynamical phenomena and their relation to the celebrated Kibble-Zurek mechanism. Finally, I will discuss the results from a recent experiment on thermal phase fluctuations in ultracold fermion rings, which have implications for quantum state preparation and manipulation.

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