Spin-imbalanced ultracold Fermi gases in a two-dimensional array of tubes
Spin-imbalanced ultracold Fermi gases in a two-dimensional array of tubes
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DOI：
10.1103/physreva.102.033311
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发表时间：
2020-05
影响因子：
2.9
通讯作者：
Bhuvanesh Sundar;Jacob A. Fry;M. Revelle;R. Hulet;K. Hazzard
中科院分区：
文献类型：
--
作者：
Bhuvanesh Sundar;Jacob A. Fry;M. Revelle;R. Hulet;K. Hazzard
受到最近的一项实验的激励[Revelle等人]。太棒了。莱特牧师。117,235301(2016)]，我们用Hartree-Fock Bogoliubov-de Gennes平均场理论计算了该系统的相图，并与实验数据进行了比较。平均场理论预言了均匀体系中完全自旋极化的正常相、部分自旋极化的正常相、自旋极化的超流相和自旋平衡的超流相。我们利用局域密度近似得到了简谐陷阱中气体的密度分布。我们将这些计算与Revelle{\em等人的实验测量以及以前未发表的数据进行了比较。我们的计算与实验测量的陷阱中相界面的密度和坐标定性一致，在中到大极化下与实验测量定量一致。我们的计算还重现了实验上观察到的不同散射长度的相界在定标管间隧道效应下的普遍标度。然而，我们的计算与低极化下的实验测量结果有定量的差异，并且未能捕捉到实验中观察到的一维到三维交叉的重要特征。这些都表明了物理超越平均场理论在实验中的重要作用。我们期望我们的数值结果将有助于未来的实验缩小对FFLO相的搜索范围。
Motivated by a recent experiment [Revelle et al. Phys. Rev. Lett. 117, 235301 (2016)] that characterized the one- to three-dimensional crossover in a spin-imbalanced ultracold gas of $^6$Li atoms trapped in a two-dimensional array of tunnel-coupled tubes, we calculate the phase diagram for this system using Hartree-Fock Bogoliubov-de Gennes mean-field theory, and compare the results with experimental data. Mean-field theory predicts fully spin-polarized normal, partially spin-polarized normal, spin-polarized superfluid, and spin-balanced superfluid phases in a homogeneous system. We use the local density approximation to obtain density profiles of the gas in a harmonic trap. We compare these calculations with experimental measurements in Revelle {\em et al.} as well as previously unpublished data. Our calculations qualitatively agree with experimentally-measured densities and coordinates of the phase boundaries in the trap, and quantitatively agree with experimental measurements at moderate-to-large polarizations. Our calculations also reproduce the experimentally-observed universal scaling of the phase boundaries for different scattering lengths at a fixed value of scaled inter-tube tunneling. However, our calculations have quantitative differences with experimental measurements at low polarization, and fail to capture important features of the one- to three-dimensional crossover observed in experiments. These suggest the important role of physics beyond-mean-field theory in the experiments. We expect that our numerical results will aid future experiments in narrowing the search for the FFLO phase.