Quantum noise detects Floquet topological phases

TL;DR

This paper demonstrates that local voltage noise spectra can effectively detect and distinguish Floquet topological phases, including bound states, in a driven open quantum system, with robustness against moderate disorder.

Contribution

It introduces a Floquet Green's function approach to identify Floquet topological phases through local noise spectra, revealing their robustness and spectral signatures.

Findings

Local noise spectra reveal Floquet topological phases.

Both regular and anomalous bound states are detectable.

Topological features are robust against moderate disorder.

Abstract

We study quantum noise in a nonequilibrium, periodically driven, open system attached to static leads. Using a Floquet Green's function formalism we show, both analytically and numerically, that local voltage noise spectra can detect the rich structure of Floquet topological phases unambiguously. Remarkably, both regular and anomalous Floquet topological bound states can be detected, and distinguished, via peak structures of noise spectra at the edge around zero-, half-, and full-drive-frequency. We also show that the topological features of local noise are robust against moderate disorder. Thus, local noise measurements are sensitive detectors of Floquet topological phases.