Showing papers by "Chris J. Vale published in 2017"

Goldstone mode and pair-breaking excitations in atomic Fermi superfluids

Abstract: Bragg spectroscopy shows the evolution of gapless Goldstone modes and single-particle-like excitations in an atomic Fermi superfluid as it crosses from a Bardeen–Cooper–Schrieffer superfluid to the Bose–Einstein condensate regime.

Superfluid density and critical velocity near the Berezinskii-Kosterlitz-Thouless transition in a two-dimensional strongly interacting Fermi gas

Abstract: We theoretically investigate superfluidity in a strongly interacting Fermi gas confined to two dimensions at finite temperature. Using a Gaussian pair fluctuation theory in the superfluid phase, we calculate the superfluid density and determine the critical temperature and chemical potential at the Berezinskii-Kosterlitz-Thouless transition. We propose that the transition can be unambiguously demonstrated in cold-atom experiments by stirring the superfluid Fermi gas using a red-detuned laser beam, to identify the characteristic jump in the local Landau critical velocity at the superfluid-normal interface, as the laser beam moves across the cloud.

Dimensional crossover in a strongly interacting ultracold atomic Fermi gas

Abstract: The crossover from two to three spatial dimensions is explored for a strongly interacting atomic Fermi superfluid. It is found that the location of the maximum critical velocity in the quasi-two-dimensional regime behaves differently from its two- and three-dimensional asymptotic scalings, and this behavior may be experimentally probed using Bragg spectroscopy.