Localization counteracts decoherence in noisy Floquet topological chains

TL;DR

This paper demonstrates that localization in Floquet topological chains can counteract decoherence of boundary states, with disorder-induced localization slowing decay and protecting topological phases.

Contribution

The study introduces a Floquet-Lindblad formalism and shows that disorder-induced localization can mitigate decoherence in Floquet topological systems.

Findings

Localized bulk states slow decay of boundary states

Disorder can protect topological phases from decoherence

Analytical and numerical validation of localization effects

Abstract

The topological phases of periodically-driven, or Floquet systems, rely on a perfectly periodic modulation of system parameters in time. Even the smallest deviation from periodicity leads to decoherence, causing the boundary (end) states to leak into the system's bulk. Here, we show that in one dimension this decay of topologically protected end states depends fundamentally on the nature of the bulk states: a dispersive bulk results in an exponential decay, while a localized bulk slows the decay down to a diffusive process. The localization can be due to disorder, which remarkably counteracts decoherence even when it breaks the symmetry responsible for the topological protection. We derive this result analytically, using a novel, discrete-time Floquet-Lindblad formalism and confirm out findings with the help of numerical simulations. Our results are particularly relevant for experiments, where disorder can be tailored to protect Floquet topological phases from decoherence.