Heteropairing and component-dependent pseudogap phenomena in an ultracold Fermi gas with different species with different masses

Ryo Hanai, Yoji Ohashi

研究成果: Article

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We investigate the superfluid phase transition and single-particle excitations in the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover regime of an unpolarized ultracold Fermi gas with mass imbalance (where two different species contributing to Cooper pairs have different atomic masses). In our recent paper [R. Hanai, Phys. Rev. A 88, 053621 (2013)PLRAAN1050-294710.1103/PhysRevA.88.053621], we showed that an extended T-matrix approximation (ETMA) can overcome the serious problem known in the ordinary (non-self-consistent) T-matrix approximation that it unphysically gives double-valued superfluid phase transition temperature Tc in the presence of mass imbalance. However, at the same time, the ETMA was also found to give the vanishing Tc in the weak-coupling and highly mass-imbalanced case. In this paper, we inspect the correctness of this ETMA result, using the self-consistent T-matrix approximation (SCTMA). We show that the vanishing Tc is an artifact of the ETMA, coming from an internal inconsistency of this theory. The superfluid phase transition actually always occurs, irrespective of the ratio of mass imbalance. We also apply the SCTMA to the pseudogap problem in a mass-imbalanced Fermi gas. We show that pairing fluctuations induce different pseudogap phenomena between the light component and heavy component. We also point out that a Li6-K40 mixture is a useful system for the realization of a heteropairing state, as well as for the study of component-dependent pseudogap phenomena.

元の言語English
記事番号043622
ジャーナルPhysical Review A - Atomic, Molecular, and Optical Physics
90
発行部数4
DOI
出版物ステータスPublished - 2014 10 21

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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