Topological phase transitions driven by next-nearest-neighbor hopping in noncentrosymmetric cold Fermi gases

We investigate the topological phase marked by the Thouless–Kohmoto–Nightingale–Nijs（TKNN） number and the phase transitions driven by the next nearest neighbor（NNN） hopping in noncentrosymmetric cold Fermi gases, both spinsinglet pairing and spin-triplet pairing are considered. There exists a critical t＇c for the NNN hopping, at which the quantum phase transition occurs, and the system changes from an Abelian（non-Abelian） phase to a non-Abelian（Abelian） one. By numerically diagonalizing the Hamiltonian in the real space, the energy spectra with edge states for different topological phases and the Majorana zero modes are discussed. Although the spin-triplet pairing does not contribute to the gap closing and the phase diagram, it induces gapless states in the presence of a magnetic field, and the TKNN number in this region is still zero.

一维自旋轨道耦合费米气体的研究进展

在超冷费米气体中,通过调节自旋轨道耦合的强度,使其与费米能量相当,可以产生许多新奇的量子效应。在过去几十年里,学者对于一维自旋轨道耦合诱导的费米气体进行了大量的理论和实验研究。与高维自旋轨道耦合相比,一维自旋轨道耦合虽然显得比较简单,但它是实验上探索基本量子物理现象的最可靠和最易行的工具。本文系统地整理了理论工作中一维自旋轨道耦合下费米气体的有趣物理现象。包括动力学振荡和孤子效应、拓扑超流、Majorana边缘态、铁磁相变和量子相位方面的理论研究。在实验中,如何实现自旋轨道耦合并且观测奇异现象,是研究的热点和难点问题。我们梳理了几种常见的实验方案和检测方法,最后对一维自旋轨道耦合诱导下费米气体方面的研究进行展望。一维自旋轨道耦合可以为初学者提供借鉴,有助于研究自旋轨道耦合调控的多体系统。本文期望为冷原子物理初学者深入理解自旋轨道耦合下多体系统的物理机制提供参考。