Phase Transition of Topological Index driven by Dephasing

TL;DR

This paper investigates how dephasing noise induces a phase transition in topological insulators, revealing the robustness of topological phases under noise and disorder through correlation matrix analysis.

Contribution

It demonstrates a finite dephasing-induced phase transition in topological insulators using correlation matrix indices, highlighting robustness near critical points.

Findings

Dephasing causes a phase transition between topological and trivial phases.

Topological indices remain robust against dephasing near critical points.

Disordered Chern insulators show resilience to dephasing close to critical disorder.

Abstract

We study topological insulators under dephasing noise. With examples of both a $2d$ Chern insulator and a $3d$ topological insulator protected by time-reversal symmetry, we demonstrate that there is a phase transition at finite dephasing strength between phases with nontrivial and trivial topological indices. Here the topological index is defined through the correlation matrix. The transition can be diagnosed through the spectrum of the whole correlation matrix or of a local subsystem. Interestingly, even if the topological insulator is very close to the topological-trivial critical point in its Hamiltonian, it still takes finite strength of dephasing to change the topological index, suggesting the robustness of topological insulators under dephasing. We further consider Chern insulators in the presence of real-space disorder, which exhibit a ground-state transition between topological and Anderson insulating phases. We find that even strongly-disordered Chern insulators, close to the critical disorder strength, exhibit robustness with respect to dephasing.