Non-Markovian continuous-time quantum walks on lattices with dynamical noise

TL;DR

This paper investigates how non-Gaussian telegraph noise affects the dynamics of continuous-time quantum walks on disordered lattices, revealing a phase transition between localized and diffusive behaviors linked to noise regimes.

Contribution

It introduces a detailed analysis of non-Gaussian telegraph noise effects on quantum walks, highlighting a noise-induced phase transition and the connection to non-Markovian dynamics.

Findings

Slow noise confines the walker to few lattice sites.

Fast noise induces a transition to quantum-classical diffusion.

Non-Markovian effects are prominent in slow noise regimes.

Abstract

We address the dynamics of continuous-time quantum walks on one-dimensional disordered lattices inducing dynamical noise in the system. Noise is described as time-dependent fluctuations of the tunneling amplitudes between adjacent sites, and attention is focused on non-Gaussian telegraph noise, going beyond the usual assumption of fast Gaussian noise. We observe the emergence of two different dynamical behaviors for the walker, corresponding to two opposite noise regimes: slow noise (i.e. strong coupling with the environment) confines the walker into few lattice nodes, while fast noise (weak coupling) induces a transition between quantum and classical diffusion over the lattice. A phase transition between the two dynamical regimes may be observed by tuning the ratio between the autocorrelation time of the noise and the coupling between the walker and the external environment generating the noise. We also address the non-Markovianity of the quantum map by assessing its memory effects, as well as evaluating the information backflow to the system. Our results suggest that the non-Markovian character of the evolution is linked to the dynamical behavior in the slow noise regime, and that fast noise induces a Markovian dynamics for the walker.