Zhou Hang, Ma Yongli
State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China.
Sci Rep. 2021 Jan 13;11(1):1228. doi: 10.1038/s41598-020-79010-w.
Recent experiments on sound waves in a unitary Fermi gas reveal many transport properties about strongly interacting fermions. Sound propagates through the coupling of momentum and heat transport, and attenuates strongly with the presence of a phase transition. In this work, focusing on the temperature regimes near and below the superfluid critical temperature [Formula: see text] in the BCS-BEC crossover, we present a Kubo-based microscopic calculation of thermal conductivity [Formula: see text], which has not attracted much attention compared to the shear viscosity. Our approach primarily addresses the contributions of the fermionic quasiparticles to thermal transport and our results return to the kinetic descriptions at high temperatures. [Formula: see text] drops upon crossing the pseudogap temperature [Formula: see text], and its temperature dependence changes below [Formula: see text]. The drops become more pronounced on the weakly coupled BCS side, where the Pauli blocking causes the upturn of [Formula: see text] above [Formula: see text]. Our calculations fit well with the sound measurement on the damping rate.
近期关于单一费米气体中声波的实验揭示了许多关于强相互作用费米子的输运性质。声音通过动量和热输运的耦合进行传播，并且在存在相变时会强烈衰减。在这项工作中，我们聚焦于BCS - BEC交叉中接近和低于超流临界温度[公式：见原文]的温度区域，给出了基于久保理论的热导率[公式：见原文]的微观计算，与剪切黏度相比，热导率此前未受到太多关注。我们的方法主要关注费米子准粒子对热输运的贡献，并且我们的结果在高温下回归到动力学描述。[公式：见原文]在越过赝能隙温度[公式：见原文]时下降，并且其温度依赖性在[公式：见原文]以下发生变化。在弱耦合的BCS一侧，下降变得更加明显，在那里泡利阻塞导致[公式：见原文]在[公式：见原文]以上出现上升。我们的计算结果与关于阻尼率的声学测量结果吻合得很好。
