An unusual phase transition in a non-Hermitian Su-Schrieffer-Heeger model

Abstract

This article studies a non-Hermitian Su-Schrieffer-Heeger (SSH) model which has periodically staggered Hermitian and non-Hermitian dimers. The changes in topological phases of the considered chiral symmetric model with respect to the introduced non-Hermiticity are studied where we find that the system supports only complex eigenspectra for all values of $u\ne 0$ and it stabilizes only non-trivial insulating phase for higher loss-gain strength. Even if the system acts as a trivial insulator in the Hermitian limit, the increase in loss-gain strength induces phase transition to non-trivial insulating phase through a (gapless) semi-metallic phase. Interesting phenomenon is observed in the case where Hermitian system acts as a non-trivial insulator. In such a situation, the introduced non-Hermiticity neither leaves the non-trivial phase undisturbed nor induces switching to trivial phase. Rather, it shows transition from non-trivial insulating phase to the same where it is mediated by the stabilization of (non-trivial) semi-metallic phase. This unusual transition between the non-trivial insulating phases through non-trivial semi-metallic phase gives rise to a question regarding the topological states of the system under open boundary conditions. So, we analyze the possibility of stable edge states in these two non-trivial insulating phases and check the characteristic difference between them. In addition, we study the nature of topological states in the case of non-trivial gapless (semi-metallic) region.

References in corpus (19)

• Topological phases in the non-Hermitian Su-Schrieffer-Heeger model
• Non-Hermitian topological phenomena: A review
• PT-Symmetry in Non-Hermitian Su-Schrieffer-Heeger model with complex boundary potentials
• Non-Hermitian route to higher-order topology in an acoustic crystal
• Observation of non-Hermitian topological Anderson insulator in quantum dynamics
• Phase transitions in a non-Hermitian Aubry-André-Harper model
• Topology of anti-parity-time-symmetric non-Hermitian Su-Schrieffer-Heeger model
• Non-Hermitian Photonic Lattices: tutorial
• Hunting for the non-Hermitian exceptional points with fidelity susceptibility
• General properties of fidelity in non-Hermitian quantum systems with PT symmetry
• Symmetry-resolved entanglement in critical non-Hermitian systems
• Properties of the non-Hermitian SSH model: role of PT-symmetry
• Compatibility of transport effects in non-Hermitian nonreciprocal systems
• Topological Microlaser with A non-Hermitian Topological Bulk
• Observation of a topological edge state stabilized by dissipation
• Topological phase diagrams of exactly solvable non-Hermitian interacting Kitaev chains
• Formation of Exceptional Points in pseudo-Hermitian Systems
• Unbalanced gain and loss in a quantum photonic system
• Finite SSH chains coupled to a two-level emitter: Hybridization of edge and emitter states