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arXiv 1301.7658cond-mat.str-elcond-mat.supr-conhep-th
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准一维非平衡费米气体FFLO态的嵌套效应和寿命效应

Nesting and lifetime effects in the FFLO state of quasi-one-dimensional imbalanced Fermi gases

Heron Caldas, Mucio A. Continentino

摘要:

受最近在一维费米原子气体中实现了Fulde-Ferrell(FF)和Larkin-Ovchinnikov(LO)态候选态的启发,我们研究了这些神秘的有限动量配对超流体中的量子相变.本文研究了零温下均匀自旋不平衡准一维费米气体中的FF态,研究了诱导相互作用对FFLO相稳定性的影响。当考虑到这一点时,我们发现从完全极化到FFLO状态的直接转变。此外,我们还考虑了准粒子态的有限寿命对正常超流不稳定性的影响。在长寿命的限制下,寿命效应是无关紧要的,并且过渡是直接从全极化到FFLO状态。然而,我们表明,对于足够短的寿命有一个量子临界点(QCP),在一个有限的值的费米波矢量的不同的准粒子的失配,我们充分的特点。在这种情况下,转变是从FFLO相位到具有增加的失配的正常部分偏振状态。

英文摘要:

Motivated by the recent experimental realization of a candidate to the Fulde-Ferrell (FF) and the Larkin-Ovchinnikov (LO) states in one dimensional (1D) atomic Fermi gases, we study the quantum phase transitions in these enigmatic, finite momentum-paired superfluids. We focus on the FF state and investigate the effects of the induced interaction on the stability of the FFLO phase in homogeneous spin-imbalanced quasi-1D Fermi gases at zero temperature. When this is taken into account we find a direct transition from the fully polarized to the FFLO state. Also, we consider the effect of a finite lifetime of the quasi-particles states in the normal-superfluid instability. In the limit of long lifetimes, the lifetime effect is irrelevant and the transition is directly from the fully polarized to the FFLO state. We show, however, that for sufficiently short lifetimes there is a quantum critical point (QCP), at a finite value of the mismatch of the Fermi wave-vectors of the different quasi-particles, that we fully characterize. In this case the transition is from the FFLO phase to a normal partially polarized state with increasing mismatch.

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