Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effects of periodic potentials on the critical velocity of superfluid
  Fermi gases in the BCS-BEC crossover   We study the effects of an external periodic potential on the critical
velocity of a superfluid Fermi gas in the crossover between the
Bardeen-Cooper-Schrieffer (BCS) phase and Bose-Einstein condensation (BEC). We
numerically solve the Bogoliubov-de Gennes equations to model a
three-dimensional (3D) gas of ultracold atoms in the superfluid phase flowing
through a 1D optical lattice. We find that when the recoil energy is comparable
to the Fermi energy, the presence of the periodic potential reduces the effect
of pair-breaking excitations. This behavior is a consequence of the peculiar
band structure of the quasiparticle energy spectrum in the lattice. When the
lattice height is much larger than the Fermi energy, the periodic potential
makes pairs of atoms to be strongly bound even in the BCS regime and
pair-breaking excitations are further suppressed. We have also found that when
the recoil energy is comparable to or larger than the Fermi energy, the
critical velocity due to long-wavelength phonon excitations shows a
non-monotonic behavior along the BCS-BEC crossover.

1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph