Fulde-Ferrell-Larkin-Ovchinnikov states in one-dimensional spin-polarized ultracold atomic Fermi gases
Fulde-Ferrell-Larkin-Ovchinnikov states in one-dimensional spin-polarized ultracold atomic Fermi gases
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一维自旋极化超冷原子费米气体中的 Fulde-Ferrell-Larkin-Ovchinnikov 态
DOI：
10.1103/physreva.76.043605
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发表时间：
2007-07
影响因子：
2.9
通讯作者：
Liu, XJ Hu, H Drummond, PD
中科院分区：
文献类型：
--
作者：
Liu, XJ Hu, H Drummond, PD
本文系统地研究了一维自旋极化费米气体中的量子相位。三个比较理论方法被用来探索在零温度下的相图：平均场理论与序参数在一个单一的平面波的形式或自洽确定的序参数使用Bogoliubov-de Gennes方程，以及精确的Bethe anomaly方法。我们发现，一个空间不均匀的Fulde-Ferrell-Larkin-Ovchinnikov相，它位于完全配对的Bardeen-Cooper-Schrieffer（BCS）状态和完全极化的正常状态之间，占主导地位的大部分的相图的均匀气体。从BCS态到Fulde-Ferrell-Larkin-Ovchinnikov相的相变是二级的，因此一维均匀极化气体中不存在相分离态。这与三维情况形成鲜明对比，在三维情况下，相分离制度被预测在相图中占据非常大的空间。我们推测，在三维的相分离相的优势预测可能是一个人工制品的非自洽平均场近似，这是大量使用的三维极化费米气体的研究。我们还考虑了谐波捕获势对相图的影响，发现在这种情况下，陷阱通常导致相分离，与三维被困气体的实验观察结果雅阁。最后，我们研究了Fulde-Ferrell-Larkin-Ovchinnikov模型的局域费米态密度。出现了双能隙结构，可作为Fulde-Ferrell-Larkin-Ovchinnikov态的实验探针。
We present a systematic study of quantum phases in a one-dimensional spin-polarized Fermi gas. Three comparative theoretical methods are used to explore the phase diagram at zero temperature: the mean-field theory with either an order parameter in a single-plane-wave form or a self-consistently determined order parameter using the Bogoliubov-de Gennes equations, as well as the exact Bethe ansatz method. We find that a spatially inhomogeneous Fulde-Ferrell-Larkin-Ovchinnikov phase, which lies between the fully paired Bardeen-Cooper-Schrieffer (BCS) state and the fully polarized normal state, dominates most of the phase diagram of a uniform gas. The phase transition from the BCS state to the Fulde-Ferrell-Larkin-Ovchinnikov phase is of second order, and therefore there are no phase separation states in one-dimensional homogeneous polarized gases. This is in sharp contrast to the three-dimensional situation, where a phase separation regime is predicted to occupy a very large space in the phase diagram. We conjecture that the prediction of the dominance of the phase separation phases in three dimension could be an artifact of the non-self-consistent mean-field approximation, which is heavily used in the study of three-dimensional polarized Fermi gases. We consider also the effect of a harmonic trapping potential on the phase diagram, and find that in this case the trap generally leads to phase separation, in accord with the experimental observations for a trapped gas in three dimensions. We finally investigate the local fermionic density of states of the Fulde-Ferrell-Larkin-Ovchinnikov ansatz. A two-energy-gap structure appears, which could be used as an experimental probe of the Fulde-Ferrell-Larkin-Ovchinnikov states.
DOI：
10.1007/bfb0120123
发表时间：
1980
期刊：
Palaeogeography, Palaeoclimatology, Palaeoecology
影响因子：
--
作者：
A. Pękalski;J. Przystawa
通讯作者：
A. Pękalski;J. Przystawa