Collective modes and stability of Bose-Fermi mixtures with a BCS-BEC crossover

Hiroyuki Shibata, Nobuhiko Yokoshi, Susumu Kurihara

    Research output: Contribution to journalArticle

    6 Citations (Scopus)

    Abstract

    We investigate an ultracold Bose-Fermi mixture with a Feshbach resonance between two hyperfine states of fermions. Using a functional integral method, we calculate collective modes associated with fermion pairs and bosons in the superfluid phase. We derive a stability condition of the mixtures that is valid in the entire region of the BCS-BEC crossover. This stability condition, which smoothly connects the well-known results obtained in both the BCS and Bose-Einstein Condensate (BEC) limits, shows that sufficiently strong fermion-boson (FB) interactions destabilize the mixtures. In order to investigate the consequence of this instability, we study the ground-state energy of both the uniformly mixed and the phase-separated states. We find that FB repulsion induces a phase separation, whereas FB attraction should cause a collapse of the mixture. The possibilities for the experimental observation of such instabilities are also discussed.

    Original languageEnglish
    Article number053615
    JournalPhysical Review A - Atomic, Molecular, and Optical Physics
    Volume75
    Issue number5
    DOIs
    Publication statusPublished - 2007 May 29

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    Bose-Einstein condensates
    crossovers
    fermions
    bosons
    attraction
    ground state
    causes
    interactions
    energy

    ASJC Scopus subject areas

    • Atomic and Molecular Physics, and Optics
    • Physics and Astronomy(all)

    Cite this

    Collective modes and stability of Bose-Fermi mixtures with a BCS-BEC crossover. / Shibata, Hiroyuki; Yokoshi, Nobuhiko; Kurihara, Susumu.

    In: Physical Review A - Atomic, Molecular, and Optical Physics, Vol. 75, No. 5, 053615, 29.05.2007.

    Research output: Contribution to journalArticle

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