Stability of superfluid Fermi gases in optical lattices

Abstract

Critical velocities of superfluid Fermi gases in optical lattices are theoretically investigated across the BCS-BEC crossover. We calculate the excitation spectra in the presence of a superfluid flow in one- and two-dimensional optical lattices. It is found that the spectrum of low-lying Anderson-Bogoliubov (AB) mode exhibits a roton-like structure in the short-wavelength region due to the strong charge density wave fluctuations, and with increasing the superfluid velocity one of the roton-like minima reaches zero before the single-particle spectrum does. This means that superfluid Fermi gases in optical lattices are destabilized due to spontaneous emission of the roton-like AB mode instead of due to Cooper pair breaking.

4 pages, 4 figures, conference proceeding for ISQM-TOKYO'08

References in corpus (2)

• Critical velocity for superfluid flow across the BEC-BCS crossover
• Phase diagram for a Bose-Einstein condensate moving in an optical lattice

Cited by in corpus (2)

• The critical velocity in the BEC-BCS crossover
• Collective excitation and stability of flow-induced gapless Fermi superfluids