Quantum Mpemba effect in chaotic systems with conservation laws

TL;DR

This paper demonstrates a quantum Mpemba effect in chaotic spin chains, where a system initially nearer to equilibrium relaxes more slowly than a farther one, due to conservation laws and hydrodynamics.

Contribution

It provides a simple, robust realization of the quantum Mpemba effect in chaotic quantum systems with conservation laws.

Findings

Initial states closer to equilibrium can relax slower than those farther away.

The effect is demonstrated explicitly in two chaotic spin chains.

Relaxation times depend on conservation laws and hydrodynamics.

Abstract

Closed chaotic quantum systems relax after a quench into a Gibbs ensemble. At late times, the relaxation speed is determined by their conservation laws and hydrodynamics. As a result, there exist pairs of initial states which thermalize to the same ensemble, yet exhibit drastically different hydrodynamic relaxation. We show in two chaotic spin chains how this enables a simple and robust realization of the quantum Mpemba effect: a system initially closer to equilibrium relaxes slower than one that starts farther away, despite both approaching the same final state.