Impurity-induced topological decomposition

TL;DR

This paper introduces a universal scheme where local impurities in non-Hermitian and Hermitian topological systems can control and decompose their global topological properties, enabling reconfigurable topological phases.

Contribution

It reveals how local impurities can sequentially modify topological invariants and induce edge states, providing a new method for tuning topological phases via local perturbations.

Findings

Impurities reduce spectral winding number stepwise in non-Hermitian lattices.

Sequential impurity control induces topological edge states in Hermitian systems.

Framework applicable across diverse physical platforms for reconfigurable topological phenomena.

Abstract

Controlling topological phases is a central goal in quantum materials and related fields, enabling applications such as robust transport and programmable edge states. Here we uncover a mechanism in which local on-site impurities act as knobs to decompose global topological properties in discrete steps. In non-Hermitian lattices with spectral winding topology, we show that each impurity sequentially reduces the winding number by one, which is directly manifested as a stepwise decomposition of quantized plateaus in the steady-state response. Based on this principle, we further develop a scheme that sequentially induces topological edge states under impurity control, in a class of Hermitian topological systems constructed by doubling the non-Hermitian ones. Our findings reveal a general scheme to tune global topological properties with local perturbations, establishing a universal framework for impurity-controlled topological phases and offering a foundation for future exploration of reconfigurable topological phenomena across diverse physical platforms.