Semi-classical theory for quantum quenches in finite transverse Ising chains

TL;DR

This paper develops a semi-classical framework to accurately predict non-equilibrium dynamics, relaxation, and recurrence phenomena in finite transverse Ising chains after quantum quenches, validated against exact free fermion results.

Contribution

It introduces a semi-classical approach to model quantum quenches in finite transverse Ising chains, providing quantitative predictions for dynamics and correlations.

Findings

Accurate predictions of relaxation times and correlation lengths.

Quantitative agreement with exact free fermion calculations.

Analysis of recurrence times and quasiperiodicity in finite systems.

Abstract

We present a quantitative semi-classical theory for the non-equilibrium dynamics of transverse Ising chains after quantum quenches, in particular sudden changes of the transverse field strength. We obtain accurate predictions for the quench dependent relaxation times and correlation lengths, and also about the recurrence times and quasiperiodicity of time dependent correlations in finite systems with open or periodic boundary conditions. We compare the quantiative predictions of our semi-classical theory (local magnetization, equal time bulk-bulk and surface-to-bulk correlations, and bulk autocorrelations) with the results from exact free fermion calculations and discuss the range of applicability of the semi-classical theory and possible generaliztaions and extensions.