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arXiv 1308.2004cond-mat.quant-gasnucl-th
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二维稀费米气体的尺度破缺和流体动力学

Scale breaking and fluid dynamics in a dilute two-dimensional Fermi gas

Clifford Chafin, Thomas Schaefer

摘要:

本文研究了与二维费米气体标度不变性反常破缺有关的两个观测量:简谐禁闭势场中的模频移和阻尼率。为此,我们计算了高温极限下二维气体的声速和体粘滞系数。我们表明,异常的声速尺度为$(2P-ρc_s^2)/P\sim z/[\log(T/E_B)]^2$,体积粘度$ζ$尺度为$ζ/η\sim z^2/[\log(T/E_B)]^6$。这里,$P$是压力,$c_s^2$是声速,$η$是剪切粘度,$z$是逸度,以及$E_B$是两体结合能。我们表明,我们的结果是一致的Vogt等人的实验结果。108,070404(2012)]。Vogt等人报道了几个百分点量级的频移$δω/ω$,以及小于背景速率$Γ/ω_0\sim 5%$的阻尼速率。

英文摘要:

We study two observables related to the anomalous breaking of scale invariance in a dilute two dimensional Fermi gas, the frequency shift and damping rate of the monopole mode in a harmonic confinement potential. For this purpose we compute the speed of sound and the bulk viscosity of the two dimensional gas in the high temperature limit. We show that the anomaly in the speed of sound scales as $(2P-ρc_s^2)/P\sim z/[\log(T/E_B)]^2$, and that the bulk viscosity $ζ$ scales as $ζ/η\sim z^2/[\log(T/E_B)]^6$. Here, $P$ is the pressure, $c_s^2$ is the speed of sound, $η$ is the shear viscosity, $z$ is the fugacity, and $E_B$ is the two-body binding energy. We show that our results are consistent with the experimental results of Vogt et al. [Phys. Rev. Lett. 108, 070404 (2012)]. Vogt et al. reported a frequency shift $δω/ω$ of the order of a few percent, and a damping rate smaller than the background rate $Γ/ω_0\sim 5%$.

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