Excitations in the BCS-BEC crossover regime of a superfluid Fermi gas with a Feshbach resonance

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We investigate single-particle excitations at T = 0 in the BCS-BEC crossover regime of a superfluid Fermi gas. We solve the Bogoliubov-de Gennes equations in a trap, including a tunable pairing interaction associated with a Feshbach resonance. We show that the single-particle energy gap Eg is dominated by the lowest-energy Andreev bound state localized at the surface of the gas, which is much smaller than the superfluid order parameter over(Δ, ̃) (r = 0) at the center of the trap. We also calculate the rf-tunneling current spectrum IF(ω). In a broad Feshbach resonance, the peak energy in IF(ω) is shown to give, not Eg, but over(Δ, ̃) (r = 0). In a narrow resonance, significant spectral weight coming from the low-energy Andreev states hides the appearance of the peak in IF(ω) at ω ≃ over(Δ, ̃) (r = 0). Our results for a broad resonance is in good agreement with the recent rf-tunneling measurement in a superfluid 6Li.

Original languageEnglish
Pages (from-to)234-238
Number of pages5
JournalPhysica C: Superconductivity and its applications
Issue numberSPEC. ISS.
Publication statusPublished - 2006 May 15
Externally publishedYes



  • BCS-BEC crossover
  • Fermion superfluidity
  • Feshbach resonance

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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