Average diagonal entropy in non-equilibrium isolated quantum systems

TL;DR

This paper analytically calculates the average diagonal entropy in isolated quantum systems out of equilibrium, comparing results with numerical simulations to validate heuristic relations and deepen understanding of entropy behavior under cyclic perturbations.

Contribution

It provides the first analytical expression for average diagonal entropy in non-equilibrium quantum systems undergoing cyclic quenches, supported by numerical validation.

Findings

Analytical formula for average diagonal entropy derived

Numerical simulations confirm heuristic relations

Insights into entropy dynamics during cyclic quenches

Abstract

The diagonal entropy was introduced as a good entropy candidate especially for isolated quantum systems out of equilibrium. Here we present an analytical calculation of the average diagonal entropy for systems undergoing unitary evolution and an external perturbation in the form of a cyclic quench. We compare our analytical findings with numerical simulations of various many-body quantum systems. Our calculations elucidate various heuristic relations proposed recently in the literature.