Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: $\pi$-junction and spontaneous current state in a superfluid Fermi gas   We discuss an idea to realize a spontaneous current in a superfluid Fermi
gas. When a polarized Fermi superfluid ($N_\up > N_\dwn$, where $N_\sigma$ is
the number of atoms in the hyperfine state described by pseudospin
$\sigma=\uparrow, \downarrow$.) is loaded onto a ring-shaped trap with a weak
potential barrier, some of excess atoms ($\Delta N=N_\uparrow-N_\downarrow$)
are localized around the barrier. As shown in our previous paper [T. Kashimura,
S. Tsuchiya, and Y. Ohashi, Phys. Rev. A \textbf{82}, 033617 (2010)], this
polarized potential barrier works as a $\pi$-junction in the sense that the
superfluid order parameter changes its sign across the barrier. Because of
this, the phase of the superfluid order parameter outside the junction is shown
to be twisted by $\pi$ along the ring, which naturally leads to a circulating
supercurrent. While the ordinary supercurrent state is obtained as a metastable
state, this spontaneous current state is shown to be more stable than the case
with no current. Our results indicate that localized excess atoms would be
useful for the manipulation of the superfluid order parameter in cold Fermi
gases.

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The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
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The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
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The categories of this paper are: physics
0
The categories of this paper are: hep-ph
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The categories of this paper are: stat
32
The categories of this paper are: atom-ph