Dynamically stable topological edge states in an extended Su-Schrieffer-Heeger ladder with balanced perturbation

TL;DR

This paper demonstrates that in an extended non-Hermitian SSH ladder, topological edge states remain dynamically stable and robust against perturbations, with spectrum invariance and potential applications in stable quantum devices.

Contribution

It reveals that balanced non-Hermitian perturbations can stabilize topological edge states in extended SSH systems, preserving bulk-boundary correspondence.

Findings

Spectrum remains unchanged under balanced perturbations.

Zero-energy edge states become coalescing states.

Edge states are robust in time domain.

Abstract

The on-site potentials may break the symmetry of a system, resulting in the loss of its original topology protected by the symmetry. In this work, we study the counteracting effect of non-Hermitian terms on real potentials, resulting in dynamically stable topological edge states. We show exactly for a class of systems that the spectrum remains unchanged in the presence of balanced perturbations. As a demonstration, we investigate an extended non-Hermitian Su-Schrieffer-Heeger(SSH) ladder. We find that the bulk-boundary correspondence still holds, and the zero-energy edge states become coalescing states. In comparison to the original SSH chain, such edge states are robust not only against local perturbations but also in the time domain. As a result, a trivial initial state can always evolve to a stable edge state. Our results provide insights for the application of time-domain stable topological quantum devices.