Finite speed heat transport in a quantum spin chain after quenched local cooling

TL;DR

This paper investigates how heat propagates at finite speed in a quantum spin chain after a local cooling quench, revealing quantum effects like intermediate heat flux plateaus due to spin wave dynamics.

Contribution

It provides a detailed comparison between semi-classical and quantum descriptions of heat transport, highlighting the finite speed of heat propagation in quantum spin chains.

Findings

Exponential decay of heat flux in semi-classical limit

Observation of intermediate heat flux plateaus in quantum case

Finite speed of heat transport attributed to spin waves

Abstract

We study the dynamics of an initially thermalized spin chain in the quantum XY-model, after sudden coupling to a heat bath of lower temperature at one end of the chain. In the semi-classical limit we see an exponential decay of the system-bath heatflux by exact solution of the reduced dynamics. In the full quantum description however, we numerically find the heatflux to reach intermediate plateaus where it is approximately constant -- a phenomenon that we attribute to the finite speed of heat transport via spin waves.