论文标题

在量子慢速动力学下表征拓扑阶段的通用理论

Generic theory of characterizing topological phases under quantum slow dynamics

论文作者

Fang, Panpan, Wang, Yi-Xiang, Li, Fuxiang

论文摘要

近年来,平衡拓扑阶段的动态表征吸引了相当大的关注。在本文中,我们对缓慢的淬灭协议下拓扑阶段的非绝热表征进行了详尽的探讨。我们首先提出了一个可以直接应用于拓扑系统的非绝热慢速淬火动力学的确切可解决的多状态Landau-Zener模型。然后,我们提出了两种不同的方案,以根据所谓的自旋反转表面来表征系统的批量拓扑。第一个需要最少数量的淬火过程,但需要测量SIS上时间平均旋转极化的梯度。第二个仅需要测量SIS上时间平均自旋偏振的值,因此可以通过引入额外的淬火过程直接表征拓扑阶段。此外,依靠降低方法的高阶SIS或带反转表面(BIS)也被推广到上述两个不同的表征方案。一个人可以从0D最高bis和0D最高级SIS上具有相反符号的点从成对的点提取拓扑不变,这极大地简化了测量策略和表征过程。用一个单词,优于突然的淬灭协议,我们证明了拓扑不变的不仅可以通过BIS的拓扑信息来捕获,还可以通过SIS捕获。特别是,可以实现基于bis和sis的拓扑阶段的直接表征。

Dynamical characterization of equilibrium topological phases has attracted considerable attention in recent years. In this paper, we make a thorough exploration of the non-adiabatic characterization of topological phases under slow quench protocol. We first propose an exactly solvable multi-state Landau-Zener model that can be directly applied to the non-adiabatic slow quench dynamics of topological systems. Then we present two different schemes to characterize the bulk topology of the system based on the so called spin inversion surface. The first one needs least number of quenching processes, but requires to measure the gradients of time-averaged spin-polarization on the SIS. The second one only needs to measure the value of time-averaged spin-polarization on the SIS, thus makes it possible to directly characterize the topological phases by introducing an extra quenching process. Moreover, high-order SIS or band inversion surface (BIS) relying on the dimension reduction approach, is also generalized to the above two different characterization schemes. One can extract the topological invariant from pairs of points with opposite signs both on the 0D highest order BIS and on the 0D highest order SIS, which greatly simplifies the measurement strategy and characterization process. In a word, superior to the sudden quench protocol, we demonstrate that the topological invariant can be captured not only by the topological information on BIS, but also on the SIS. In particular, direct characterization of topological phases based on BIS and SIS can be realized.

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