Relaxation of isolated quantum systems beyond chaos

TL;DR

This paper investigates how isolated quantum systems relax to equilibrium and uncovers a universal relation between relaxation and initial state delocalization, regardless of whether the system is regular or chaotic.

Contribution

It reveals a universal relation between relaxation dynamics and initial state delocalization that holds across integrable and chaotic quantum systems.

Findings

Relaxation correlates with initial state delocalization.

Universal relation holds regardless of chaos presence.

Study of two tunable many-body quantum systems.

Abstract

In classical statistical mechanics there is a clear correlation between relaxation to equilibrium and chaos. In contrast, for isolated quantum systems this relation is -- to say the least -- fuzzy. In this work we try to unveil the intricate relation between the relaxation process and the transition from integrability to chaos. We study the approach to equilibrium in two different many body quantum systems that can be parametrically tuned from regular to chaotic. We show that a universal relation between relaxation and delocalization of the initial state in the perturbed basis can be established regardless of the chaotic nature of system.