Extrinsic topology of Floquet anomalous boundary states in quantum walks
Extrinsic topology of Floquet anomalous boundary states in quantum walks
复制标题
量子行走中 Floquet 反常边界态的外在拓扑
DOI：
10.1103/physrevb.105.094306
复制
发表时间：
2022
影响因子：
3.7
通讯作者：
and Masatoshi Sato
中科院分区：
文献类型：
--
作者：
Takumi Bessho;Ken Mochizuki;Hideaki Obuse;and Masatoshi Sato
体-边界对应是拓扑相的基本原理，其中体拓扑确定无间隙边界状态。在另一方面，它已被称为角或铰链模式在高阶拓扑绝缘体可能会出现由于“外在”的拓扑结构的边界，即使当体积拓扑数是平凡的。本文发现量子行走中的Floquet反常边界态具有类似的外赋拓扑性质。与高阶拓扑绝缘体相反，量子行走中的非本征拓扑即使对于一阶拓扑相也是明显的。给出了量子行走中的外赋拓扑的拓扑表，并通过具体例子说明了Floquet反常边界态的外赋性质。
Bulk-boundary correspondence is a fundamental principle for topological phases where bulk topology determines gapless boundary states. On the other hand, it has been known that corner or hinge modes in higher-order topological insulators may appear due to “extrinsic” topology of the boundaries even when the bulk topological numbers are trivial. In this paper, we find that Floquet anomalous boundary states in quantum walks have similar extrinsic topological natures. In contrast to higher-order topological insulators, the extrinsic topology in quantum walks is manifest even for first-order topological phases. We present the topological table for extrinsic topology in quantum walks and illustrate extrinsic natures of Floquet anomalous boundary states in concrete examples.