Topological Reality Switch: Towards Bulk-Boundary Selective Lasing

TL;DR

This paper introduces a topological reality switch in a 2D non-Hermitian SSH model that enables controllable real spectra and boundary-dependent phase transitions, advancing bulk-boundary control for lasing applications.

Contribution

It presents a novel topological reality switch mechanism in a 2D non-Hermitian system, enabling boundary-dependent spectral control and phase transitions.

Findings

Real spectrum can be controlled via boundary conditions.

A topological phase transition occurs during the reality switch.

The work enables selective bulk-boundary control for lasing.

Abstract

The emergence of complex spectra in non-Hermitian systems causes dramatic changes even under weak perturbations, significantly hindering their precise control for study and integration into practical applications. Achieving a controlled method to generate a real spectrum in non-Hermitian systems has long been a key objective in the field. In this study, we explore the 2D non-Hermitian Su-Schrieffer-Heeger (SSH) model and introduce a reality switch that allows for the controllable induction of a real spectrum depending on the imposed boundary condition. We show that a topological phase transition in the complex gap accompanies the switching process. Our work lays the cornerstone for developing a selective bulk-boundary control mechanism for the gain and lasing behaviors in non-Hermitian systems.