论文标题
有吸引力的极化费米气体的演变：从极地的费米液体到fulde-ferrell-larkin-ovchinnikov量子的非弗尔米液体
Evolution of an attractive polarized Fermi gas: From a Fermi liquid of polarons to a non-Fermi liquid at the Fulde-Ferrell-Larkin-Ovchinnikov quantum critical point
论文作者
论文摘要
The evolution of an attractive polarized two-component Fermi gas at zero temperature is analyzed as its polarization is progressively decreased, from full polarization (corresponding to the polaronic limit) down to a critical polarization when superfluidity sets in. This critical polarization and the nature of the associated superfluid instability are determined within a fully self-consistent $t$-matrix approach implemented exactly at zero temperature.这样，在整个BCS-BEC交叉上构建了零温度下的极化-VS耦合相图。根据两个组分之间粒子间相互作用的耦合强度，超氟不稳定性可以朝向Fulde-Ferrel-Larkin-ovchinnikov（FFLO）相，也可以朝向标准的极化BCS相。正常费米气体中准粒子参数极化的演变在两种情况下截然不同。当不稳定性朝向极化的BCS超流体时，两个费米表面接近的准颗粒对于所有极化都保持良好的定义。当不稳定性朝向FFLO超流体时，前体效应在接近FFLO量子临界点（QCP）时就会显而易见，其中准粒子残基消失了，有效的质量差异。这种行为导致了费米液体的准粒子图像特征的完全分解，类似于在抗铁磁QCP处的重绒毛材料中发生的情况。在单位性时，在有限温度下进一步研究了该系统，从而可以在与基础FFLO QCP相关的温度-VS极化相图中识别非FERMI液体区域。
The evolution of an attractive polarized two-component Fermi gas at zero temperature is analyzed as its polarization is progressively decreased, from full polarization (corresponding to the polaronic limit) down to a critical polarization when superfluidity sets in. This critical polarization and the nature of the associated superfluid instability are determined within a fully self-consistent $t$-matrix approach implemented exactly at zero temperature. In this way, the polarization-vs-coupling phase diagram at zero temperature is constructed throughout the whole BCS-BEC crossover. Depending on the coupling strength of the inter-particle interaction between the two components, the superfluid instability can be either toward a Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) phase or toward a standard polarized BCS phase. The evolution with polarization of the quasi-particle parameters in the normal Fermi gas turns out to be notably different in the two cases. When the instability is toward a polarized BCS superfluid, quasi-particles in the proximity of the two Fermi surfaces remain well defined for all polarizations. When the instability is instead toward an FFLO superfluid, precursor effects become apparent upon approaching the FFLO quantum critical point (QCP), where the quasi-particle residues vanish and the effective masses diverge. This behavior leads to a complete breakdown of the quasi-particle picture characteristic of a Fermi liquid, similarly to what occurs in heavy-fermion materials at an antiferromagnetic QCP. At unitarity, the system is further investigated at finite temperature, making it possible to identify a non-Fermi liquid region in the temperature-vs-polarization phase diagram associated with the underlying FFLO QCP.
