盐城工学院Beibing Huang团队研究了吸引人的Qi-Wu-Zhang-Hubbard模型中的阻塞超流体。2025年4月15日出版的《物理评论A》杂志发表了这项成果。

基于最近实现的超冷费米子自旋-轨道耦合最小量子异常霍尔相Qi-Wu-Zhang （QWZ）模型，研究小组引入了现场吸引相互作用，并在平均场水平上绘制了Qi-Wu-Zhang- hubbard （QWZH）模型的拓扑相图。结果表明，在相空间的扩展区域，除了常规的非零陈氏数的手性拓扑超流体（TSs）外，还存在零陈氏数的阻塞超流体（OSF）。

该相的特征是完全脱离体能带的无间隙边缘态和两个两个数字。研究组发现OSF中的无间隙边缘态受到粒子-空穴对称性和无序性的保护。OSF的出现表明，仅仅用陈氏数来标记二维D类中的ts是不够的。这些不同的拓扑相在吸引QWZH模型可以检测实验自旋分辨飞行时间成像。

研究组还绘制了具有一维自旋-轨道耦合的吸引QWZH模型的相图，并找到了一系列具有无间隙狄拉克点的TSs。考虑到QWZ模型的成功实现以及在操纵冷原子系统方面取得的巨大进展，该工作为未来在冷费米子系统中实现OSF提供了一条可能的途径。

附：英文原文

Title: Obstructed superfluid in the attractive Qi-Wu-Zhang-Hubbard model

Author: Beibing Huang, Chaofei Liu, Ning Xu

Issue&Volume: 2025/04/15

Abstract: Motivated by the recent realization of the Qi-Wu-Zhang (QWZ) model for the minimal spin-orbit-coupled quantum anomalous Hall phase in ultracold fermions, we introduce the on-site attractive interaction and map out the topological phase diagram for the Qi-Wu-Zhang-Hubbard (QWZH) model at the mean-field level. We show that, in addition to the conventional chiral topological superfluids (TSs) with nonzero Chern number, there is also an obstructed superfluid (OSF) with zero Chern number in the extended region of phase space. This phase is characterized by gapless edge states completely detaching from the bulk energy bands and two 2 numbers. We find the gapless edge states in OSF are protected by particle-hole symmetry and robust for the disorder. The appearance of OSF demonstrates that it is not sufficient to label TSs in the two-dimensional D class only by Chern numbers. These different topological phases in the attractive QWZH model can be detected experimentally by spin-resolved time-of-flight imaging. We also plot the phase diagram of the attractive QWZH model with one-dimensional spin-orbit coupling and find a series of TSs with gapless Dirac points. Considering the successful realization of the QWZ model and the tremendous progress in manipulating cold atom systems, our work provides a possible route to realize OSF in cold fermionic systems in the future.

DOI: 10.1103/PhysRevA.111.043310

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.111.043310