Sound propagation and oscillations of a superfluid Fermi gas in the presence of a 1D optical lattice

TL;DR

This paper develops a hydrodynamic theory for superfluid Fermi gases in a 1D optical lattice, analyzing sound propagation, stability, and collective oscillations, with calculations in the weakly interacting BCS limit.

Contribution

It introduces a hydrodynamic framework for Fermi superfluids in periodic potentials, including calculations of key parameters and stability conditions.

Findings

Calculated sound velocity and effective mass in the BCS limit.

Analyzed stability conditions against elementary excitations.

Evaluated center of mass oscillation frequency in harmonic traps.

Abstract

We develop the hydrodynamic theory of Fermi superfluids in the presence of a periodic potential. The relevant parameters governing the propagation of sound (compressibility and effective mass) are calculated in the weakly interacting BCS limit. The conditions of stability of the superfluid motion with respect to creation of elementary excitations are discussed. We also evaluate the frequency of the center of mass oscillation when the superfluid gas is additionally confined by a harmonic trap.