Validating simple dynamical simulations of the unitary Fermi gas
Validating simple dynamical simulations of the unitary Fermi gas
复制标题
验证酉费米气体的简单动力学模拟
DOI：
10.1103/physreva.90.043638
复制
发表时间：
2013
影响因子：
2.9
通讯作者：
Rishi Sharma
中科院分区：
文献类型：
--
作者：
M. Forbes;Rishi Sharma
我们提出了一个使用超流局域密度近似（SLDA）和一个简化的玻色子模型，扩展的托马斯费米（ETF）与酉状态方程的幺正费米子气体的模拟动力学之间的比较。小振幅波动在两种理论中具有相似的动力学，频率远低于对断裂阈值，波矢量远小于费米动量，低频线性响应与令人惊讶的大波矢量匹配良好，甚至高达费米动量。对于非线性动态，如涡流产生，ETF提供了SLDA动态的半定量描述，只要波动在货币对突破阈值附近没有显著的力量，否则ETF的动态就不能被信任。ETF中的非线性倾向于产生高频波动，并且没有正常分量从超流中移除这种能量，像涡旋晶格这样的特征不能像SLDA中那样松弛和结晶。通过考虑差距平方的近似守恒性，我们提出了一个验证ETF动态可靠性的启发式诊断：$\int|德尔塔|^2 $。
We present a comparison between simulated dynamics of the unitary fermion gas using the superfluid local density approximation (SLDA) and a simplified bosonic model, the extended Thomas Fermi (ETF) with a unitary equation of state. Small amplitude fluctuations have similar dynamics in both theories for frequencies far below the pair breaking threshold and wave vectors much smaller than the Fermi momentum, and the low frequency linear responses match well for surprisingly large wave vectors, even up to the Fermi momentum. For non-linear dynamics such as vortex generation, the ETF provides a semi-quantitative description of SLDA dynamics as long as the fluctuations do not have significant power near the pair breaking threshold, otherwise the dynamics of the ETF cannot be trusted. Nonlinearities in the ETF tends to generate high-frequency fluctuations, and with no normal component to remove this energy from the superfluid, features like vortex lattices cannot relax and crystallize as they do in the SLDA. We present a heuristic diagnostic for validating the reliability of ETF dynamics by considering the approximate conservation of square of the gap: $\int|\Delta|^2$.