Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Collective modes and superflow instabilities of strongly correlated
  Fermi superfluids   We study the superfluid phase of the one-band attractive Hubbard model of
fermions as a prototype of a strongly correlated s-wave fermion superfluid on a
lattice. We show that the collective mode spectrum of this superfluid exhibits,
in addition to the long wavelength sound mode, a sharp roton mode over a wide
range of densities and interaction strengths. We compute the sound velocity and
the roton gap within a generalized random phase approximation (GRPA) and show
that the GRPA results are in good agreement, at strong coupling, with a spin
wave analysis of the appropriate strong-coupling pseudospin model. We also
investigate, using this two-pronged approach, the breakdown of superfluidity in
the presence of a supercurrent. We find that the superflow can break down at a
critical flow momentum via several distinct mechanisms - depairing, Landau
instabilities or dynamical instabilities - depending on the dimensionality, the
interaction strength and the fermion density. The most interesting of these
instabilities is a charge modulation dynamical instability which is distinct
from previously studied dynamical instabilities of Bose superfluids. The charge
order associated with this instability can be of two types: (i) a commensurate
checkerboard modulation driven by softening of the roton mode at the Brillouin
zone corner, or, (ii) an incommensurate density modulation arising from
superflow-induced finite momentum pairing of Bogoliubov quasiparticles. We
elucidate the dynamical phase diagram showing the critical flow momentum of the
leading instability over a wide range of fermion densities and interaction
strengths and point out implications of our results for experiments on cold
atom fermion superfluids in an optical lattice.

1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc