Topological properties of non-Hermitian Creutz ladders

• 作者: Hui-Qiang Liang Linhu Li
• 来源期刊: 中国物理B（英文版）
• 年，卷（期）: 2022,（1）
• 所属期刊栏目: SPECIAL TOPIC— Non-Hermitian physics
• 页码范围: 64-77
• 页数: 14页
• 语种: 英文
• DOI: 10.1088/1674-1056/ac3991

摘要

We study topological properties of the one-dimensional Creutz ladder model with different non-Hermitian asymmet-ric hoppings and on-site imaginary potentials,and obtain phase diagrams regarding the presence and absence of an energy gap and in-gap edge modes.The non-Hermitian skin effect (NHSE),which is known to break the bulk-boundary corre-spondence (BBC),emerges in the system only when the non-Hermiticity induces certain unbalanced non-reciprocity along the ladder.The topological properties of the model are found to be more sophisticated than that of its Hermitian counter-part,whether with or without the NHSE.In one scenario without the NHSE,the topological winding is found to exist in a two-dimensional plane embedded in a four-dimensional space of the complex Hamiltonian vector.The NHSE itself also possesses some unusual behaviors in this system,including a high spectral winding without the presence of long-range hop-pings,and a competition between two types of the NHSE,with the same and opposite inverse localization lengths for the two bands,respectively.Furthermore,it is found that the NHSE in this model does not always break the conventional BBC,which is also associated with whether the band gap closes at exceptional points under the periodic boundary condition.