Details

Autor(en) / Beteiligte

• Liu, Tao
• Zhang, Yu-Ran
• Ai, Qing
• Gong, Zongping
• Kawabata, Kohei
• Ueda, Masahito
• Nori, Franco

Titel

Second-Order Topological Phases in Non-Hermitian Systems

Ist Teil von

• Physical review letters, 2019-02, Vol.122 (7), p.076801-076801, Article 076801

Ort / Verlag

United States: American Physical Society

Erscheinungsjahr

2019

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• 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.