Regular Article

Density matrix of chaotic quantum systems

Department of Physics, Zhejiang Normal University, Jinhua 321004, P.R. China

^a e-mail: wangpei@zjnu.cn

Received: 8 February 2020
Received in final form: 15 August 2020
Accepted: 9 September 2020
Published online: 14 October 2020

Abstract

The nonequilibrium dynamics in chaotic quantum systems denies a fully understanding up to now, even if thermalization in the long-time asymptotic state has been explained by the eigenstate thermalization hypothesis which assumes a universal form of the observable matrix elements in the eigenbasis of Hamiltonian. It was recently proposed that the density matrix elements have also a universal form, which can be used to understand the nonequilibrium dynamics at the whole time scale, from the transient regime to the long-time steady limit. In this paper, we numerically test these assumptions for density matrix in the models of spins.