Excitation properties and effects of mass imbalance in the BCS-BEC crossover regime of an ultracold Fermi gas

Ryo Hanai, Takashi Kashimura, Ryota Watanabe, Daisuke Inotani, Yoji Ohashi

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22 Citations (Scopus)


We investigate single-particle properties of a mass-imbalanced Fermi gas in the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover region. In the presence of mass imbalance, we point out that the ordinary T-matrix approximation, which has been extensively used to clarify various BCS-BEC crossover physics in the mass-balanced case, unphysically gives a double-valued solution in terms of the superfluid phase transition temperature Tc in the crossover region. To overcome this serious problem, we include higher order strong-coupling corrections beyond the T-matrix level. Using this extended T-matrix theory, we calculate single-particle excitations in the normal state above Tc. The so-called pseudogap phenomena originating from pairing fluctuations are shown to be different between the light-mass component and heavy-mass component, which becomes more remarkable at higher temperatures. Since Fermi condensates with hetero-Cooper pairs have recently been discussed in various fields, such as exciton (polariton) condensates as well as color superconductivity, our results would be useful for the further development of Fermi superfluid physics, beyond the conventional superfluid state with homo-Cooper pairs.

Original languageEnglish
Article number053621
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number5
Publication statusPublished - 2013 Nov 18

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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