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arXiv 1001.2085cond-mat.quant-gascond-mat.str-el
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强相互作用费米气体的普适热力学:理论与实验

Universal thermodynamics of a strongly interacting Fermi gas: theory versus experiment

Hui Hu, Xia-Ji Liu, Peter D. Drummond

摘要:

强相互作用的稀费米气体表现出标度不变的普遍热力学行为。众所周知,这在理论上很难理解,因为没有一个小的相互作用参数。在这里,我们提出了一个系统的比较,从不同的量子多体理论的理论预测与最近的实验数据Nascimbene等。(arXiv:0911.0747v1).我们的比较没有可调参数,无论是理论上还是实验上。一个简单的高斯对波动理论给出了最好的定量协议在阈值以下的超流态。在正常状态下,我们还使用量子集团展开理论计算状态方程,并详细探讨其适用于低温。利用热力学函数$S(T)$的精确实验结果,我们确定了在么正性条件下被囚禁的费米气体的温度$T$作为非相互作用温度$T_{i}$的函数,该温度可以通过绝热扫描到自由气体极限而得到.通过分析最近的实验数据,我们发现在谐波势阱中存在一个正常-超流转变温度$(T/T_{F})_{c}=0.19\pm0.02$或$(T_{i}/T_{F})_{c}=0.16\pm0.02$,其中$T_{F}$是被囚禁的理想、无相互作用的费米气体的费米温度.

英文摘要:

Strongly interacting, dilute Fermi gases exhibit a scale-invariant, universal thermodynamic behaviour. This is notoriously difficult to understand theoretically because of the absence of a small interaction parameter. Here we present a systematic comparison of theoretical predictions from different quantum many-body theories with recent experimental data of Nascimbene et. al. (arXiv:0911.0747v1). Our comparisons have no adjustable parameters, either theoretically or experimentally. A simple Gaussian pair fluctuation theory is shown to give the best quantitative agreement in the superfluid state below threshold. In the normal state, we also calculate the equation of state by using a quantum cluster expansion theory and explore in detail its applicability to low temperatures. Using the accurate experimental result for the thermodynamic function $S(T)$, we determine the temperature $T$ of a trapped Fermi gas at unitarity as a function of a non-interacting temperature $T_{i}$ which can be obtained by an adiabatic sweep to the free gas limit. By analyzing the recent experimental data, we find a normal-superfluid transition temperature $(T/T_{F})_{c}=0.19\pm0.02$ or $(T_{i}/T_{F})_{c}=0.16\pm0.02$ in a harmonic trap, where $T_{F}$ is the Fermi temperature for a trapped ideal, non-interacting Fermi gas.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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