Superfluid density in the BCS-BEC crossover regime of a Fermi superfluid

Y. Ohashi, N. Fukushima, H. Matsumoto, E. Taylor, A. Griffin

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


We investigate the superfluid carrier density ρs in the BCS-BEC crossover regime of a Fermi superfluid at finite temperatures. Including pairing fluctuations within a Gaussian approximation, we calculate the superfluid order parameter, chemical potential, and ρs in a consistent manner in the whole BCS-BEC crossover region. In the weak-coupling BCS regime, the temperature dependence of ρs is dominated by single-particle excitations accompanied by thermal dissociation of Cooper pairs. In the strong-coupling BEC regime, we show that single-particle excitations become less dominant and thermal excitations of collective Bogoliubov mode become important for ρs. We clarify how the weak-coupling BCS result smoothly changes into the strong-coupling BEC result, as one increases the strength of a pairing interaction.

Original languageEnglish
Pages (from-to)599-604
Number of pages6
JournalPhysica C: Superconductivity and its applications
Issue number7-10
Publication statusPublished - 2008 Apr 1


  • BCS-BEC crossover
  • Superfluid density
  • Ultracold Fermi gas

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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