{pi} junction and spontaneous current state in a superfluid Fermi gas

Journal Article · Fri Jul 15 04:00:00 EDT 2011 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.84.013609· OSTI ID:22051350

Kashimura, Takashi ^[1]; Tsuchiya, Shunji ^[2]; Ohashi, Yoji ^[1]

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1. Department of Physics, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)
2. Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)

We discuss an idea to realize a spontaneous current in a superfluid Fermi gas. When a polarized Fermi superfluid (N{sub {up_arrow}}>N{sub {down_arrow}}, where N{sub {sigma}} is the number of atoms in the hyperfine state described by pseudospin {sigma}={up_arrow},{down_arrow}) is loaded onto a ring-shaped trap with a weak potential barrier, some excess atoms ({Delta}N=N{sub {up_arrow}}-N{sub {down_arrow}}) are localized around the barrier. As shown in our previous paper [T. Kashimura, S. Tsuchiya, and Y. Ohashi, Phys. Rev. A 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.

• OSTI ID: 22051350
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 1 Vol. 84; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ATOMS
CURRENTS
FERMI GAS
JOSEPHSON JUNCTIONS
METASTABLE STATES
ORDER PARAMETERS
SUPERFLUIDITY