The nature of the normal phase of an ultracold Fermi gas in the BCS-BEC crossover regime is an interesting and unresolved question. As interactions increase, while the many-body ground state remains a condensate of paired fermions, the normal state must evolve from a Fermi liquid to a Bose gas of molecules. In this thesis, I present a technique to spatially select a homogeneous sample from the center of a trapped gas to explore this crossover. Combining this technique with RF spectroscopy, we locally measure Tan\textquoterights contact as a function of temperature and compare to various many-body theories. In another experiment, we measure the distribution of single-particle energies and momenta for a normal gas across the BCS-BEC crossover. We find that the data fit well to a two-part function that includes a peak corresponding to fermionic quasi particles and an \textquotedblleftincoherent background\textquotedblright that is modeled using the dispersion of thermal molecules. I also describe the construction of a new-generation Fermi gas apparatus.
CY - Boulder, CO DA - 2017-05 N2 -The nature of the normal phase of an ultracold Fermi gas in the BCS-BEC crossover regime is an interesting and unresolved question. As interactions increase, while the many-body ground state remains a condensate of paired fermions, the normal state must evolve from a Fermi liquid to a Bose gas of molecules. In this thesis, I present a technique to spatially select a homogeneous sample from the center of a trapped gas to explore this crossover. Combining this technique with RF spectroscopy, we locally measure Tan\textquoterights contact as a function of temperature and compare to various many-body theories. In another experiment, we measure the distribution of single-particle energies and momenta for a normal gas across the BCS-BEC crossover. We find that the data fit well to a two-part function that includes a peak corresponding to fermionic quasi particles and an \textquotedblleftincoherent background\textquotedblright that is modeled using the dispersion of thermal molecules. I also describe the construction of a new-generation Fermi gas apparatus.
PB - University of Colorado Boulder PP - Boulder, CO PY - 2017 EP - 148 TI - Probing local quantities in a strongly interacting Fermi gas and the construction of an ultracold Fermi gas apparatus VL - Ph.D. ER -