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

Abstract

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.

Authors:
 [1];  [2];  [3];  [1];  [3]
  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)
  3. (JST), 4-1-8 Honcho, Saitama 332-0012 (Japan)
Publication Date:
OSTI Identifier:
22051350
Resource Type:
Journal Article
Journal Name:
Physical Review. A
Additional Journal Information:
Journal Volume: 84; Journal Issue: 1; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1050-2947
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ATOMS; CURRENTS; FERMI GAS; JOSEPHSON JUNCTIONS; METASTABLE STATES; ORDER PARAMETERS; SUPERFLUIDITY

Citation Formats

Kashimura, Takashi, Tsuchiya, Shunji, CREST, Ohashi, Yoji, and CREST. {pi} junction and spontaneous current state in a superfluid Fermi gas. United States: N. p., 2011. Web. doi:10.1103/PHYSREVA.84.013609.
Kashimura, Takashi, Tsuchiya, Shunji, CREST, Ohashi, Yoji, & CREST. {pi} junction and spontaneous current state in a superfluid Fermi gas. United States. doi:10.1103/PHYSREVA.84.013609.
Kashimura, Takashi, Tsuchiya, Shunji, CREST, Ohashi, Yoji, and CREST. Fri . "{pi} junction and spontaneous current state in a superfluid Fermi gas". United States. doi:10.1103/PHYSREVA.84.013609.
@article{osti_22051350,
title = {{pi} junction and spontaneous current state in a superfluid Fermi gas},
author = {Kashimura, Takashi and Tsuchiya, Shunji and CREST and Ohashi, Yoji and CREST},
abstractNote = {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.},
doi = {10.1103/PHYSREVA.84.013609},
journal = {Physical Review. A},
issn = {1050-2947},
number = 1,
volume = 84,
place = {United States},
year = {2011},
month = {7}
}