Dynamical Signatures of Liouvillian Flat Band

TL;DR

This paper investigates how flat bands in the Liouvillian spectrum affect the relaxation dynamics of open quantum systems, revealing unique decay behaviors and dynamical localization phenomena.

Contribution

It introduces the concept of Liouvillian flat bands and demonstrates their impact on relaxation dynamics and localization in a Lindblad master equation framework.

Findings

Flat Liouvillian spectrum leads to uniform decay rates in particle relaxation.

Dispersionless real or imaginary parts cause oscillating or forked relaxation behaviors.

Liouvillian flat band induces dynamical localization, halting propagation of local perturbations.

Abstract

Although flat-band structures have attracted intensive studies in condensed matter and optical physics due to their eigenstates exhibiting huge degeneracy and allowing for the localization of wave packet, it is not clear how the flat band of Liouvillian influences the relaxation dynamics of open quantum systems. To this end, we study the dynamical signatures of Liouvillian flat band in the scheme of Lindblad master equation. Considering a chain model with gain and loss, we demonstrate three kinds of band dispersion of Liouvillian: flat bland, dispersionless only in the real part and imaginary part, and capture their dynamical signatures: when the rapidity spectrum of Liouvillian is flat, the particle numbers in different sites relax to its steady state value with the same decay rate; when the real or imaginary part of rapidity spectrum is dispersionless, the relaxation behaviors have oscillating or forked characteristics. We also unveil that the Liouvillian flat band can lead to dynamical localization, which is characterized by the halt of propagation of a local perturbation on the steady state.