Second-Order Topological Phases in Non-Hermitian Systems

被引：424

作者：

Liu, Tao ^{[1
]}

Zhang, Yu-Ran ^{[1
,2
]}

Ai, Qing ^{[1
,3
]}

Gong, Zongping ^{[4
]}

Kawabata, Kohei ^{[4
]}

Ueda, Masahito ^{[4
,5
]}

Nori, Franco ^{[1
,6
]}

机构：

[1] RIKEN, Theoret Quantum Phys Lab, Cluster Pioneering Res, Wako, Saitama 3510198, Japan

[2] Beijing Computat Sci Res Ctr, Beijing 100193, Peoples R China

[3] Beijing Normal Univ, Dept Phys, Appl Opt Beijing Area Major Lab, Beijing 100875, Peoples R China

[4] Univ Tokyo, Dept Phys, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1130033, Japan

[5] RIKEN, CEMS, Wako, Saitama 3510198, Japan

[6] Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA

来源：

PHYSICAL REVIEW LETTERS | 2019年 / 122卷 / 07期

基金：

日本科学技术振兴机构; 中国博士后科学基金;

关键词：

PSEUDO-HERMITICITY; REALIZATION; SYMMETRY; HAMILTONIANS; INSULATOR; PHYSICS; NUMBER; STATES; MATTER; LASER;

D O I：

10.1103/PhysRevLett.122.076801

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

A d-dimensional second-order topological insulator (SOTI) can host topologically protected (d - 2)-dimensional gapless boundary modes. Here, we show that a 2D non-Hermitian SOTI can host zero-energy modes at its corners. In contrast to the Hermitian case, these zero-energy modes can be localized only at one corner. A 3D non-Hermitian SOTI is shown to support second-order boundary modes, which are localized not along hinges but anomalously at a corner. The usual bulk-corner (hinge) correspondence in the second-order 2D (3D) non-Hermitian system breaks down. The winding number (Chern number) based on complex wave vectors is used to characterize the second-order topological phases in 2D (3D). A possible experimental situation with ultracold atoms is also discussed. Our work lays the cornerstone for exploring higher-order topological phenomena in non-Hermitian systems.

引用

页数：8

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