Topological phase transition of the extended non-Hermitian Su-Schrieffer-Heeger model

Abstract

Herein, the topological phase transition of an extended non-Hermitian Su-Schrieffer-Heeger model with both asymmetric nearest-neighbor and next-nearest-neighbor hopping is investigated. Moreover, an analytical method to determine the topological phase transition point under the open boundary condition is developed through a combination of the conditions required for constructing the generalized Brillouin zone and the topological invariants associated with distinct topological regions. The analytical results obtained thereafter are observed to be consistent with the analysis of the numerical energy spectrum under the open boundary condition. Finally, the bulk-boundary correspondence in such a non-Hermitian system is also discussed.