Quantum Quench from a Thermal Initial State

TL;DR

This paper investigates the dynamics of free bosons after a quantum quench from a thermal state, showing subsystems reach thermal states with possible lower effective temperatures, and explores lattice effects and other quenches.

Contribution

It extends quantum quench analysis to thermal initial states, revealing thermalization behavior and temperature dynamics in free boson systems.

Findings

Subsystems reach stationary thermal states with momentum-dependent temperatures

Effective temperature can be lower than initial temperature in some cases

Lattice effects and other quench types are analyzed

Abstract

We consider a quantum quench in a system of free bosons, starting from a thermal initial state. As in the case where the system is initially in the ground state, any finite subsystem eventually reaches a stationary thermal state with a momentum-dependent effective temperature. We find that this can, in some cases, even be lower than the initial temperature. We also study lattice effects and discuss more general types of quenches.