Date of Award
Fall 2023
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Physics
First Advisor
Navon, Nir
Abstract
Ultracold atomic gases, traditionally produced in harmonic traps, have been a successful platform in studying many-body problems. In recent years, the realization of homogeneous quantum gases in optical box potentials has opened up new opportunities to study complex problems without the complications arising from the density inhomogeneity, and allows for more direct comparisons with theories. In this thesis, we present the production and the study of a homogeneous Fermi gas consisting of Lithium-6 atoms. We begin by examining the experimental setup for cooling and trapping atoms, with a particular emphasis on how the box trapping potential is implemented. We then present three projects that take advantage of this clean experimental setting: (I) Fermionic Joule-Thomson effect. We investigate the temperature dynamics of a homogeneous Fermi gas during isenthalpic rarefaction. We observe heating for both ideal and unitary Fermi gases, in contrast to cooling previously seen in excited-population-saturated uniform Bose gases. (II) The stability of the repulsive Fermi gas with contact interactions. This many-body repulsive 'branch' is metastable towards the formation of Feshbach bound states via three-body recombination. We measure the recombination coefficient and observe that it scales universally with the average kinetic energy per particle and two-body scattering length. (III) Loss dynamics in a strongly interacting Fermi gas. We measure the lifetime of a homogeneous Fermi gas in the BEC-BCS crossover and calibrate the scaling relation between density loss rate and density. We explore the possibility that the loss is induced by the box light which has a wavelength of 639~nm.
Recommended Citation
Ji, Yunpeng, "Many-Body Physics with a Ultracold Uniform Fermi Gas" (2023). Yale Graduate School of Arts and Sciences Dissertations. 1118.
https://elischolar.library.yale.edu/gsas_dissertations/1118
