Prethermalization in one-dimensional quantum many-body systems with confinement

TL;DR

This paper investigates the prethermalization process in one-dimensional quantum many-body systems with confinement, revealing multiple relaxation stages and the role of meson-like bound states in the dynamics.

Contribution

It demonstrates the existence of a prethermal state with conserved meson number and details the multi-stage thermalization process in confined quantum systems.

Findings

Prethermal state described by a Gibbs ensemble with conserved meson number.

Relaxation involves rare meson creation events leading to an avalanche of scattering.

True thermal equilibrium is reached only after a much longer timescale, violating meson number conservation.

Abstract

Unconventional nonequilibrium phases with restricted correlation spreading and slow entanglement growth have been proposed to emerge in systems with confined excitations, calling their thermalization dynamics into question. Here, we show that in confined systems the thermalization dynamics after a quantum quench instead exhibits multiple stages with well separated time scales. As an example, we consider the confined Ising spin chain, in which domain walls in the ordered phase form bound states reminiscent of mesons. The system first relaxes towards a prethermal state, described by a Gibbs ensemble with conserved meson number. The prethermal state arises from rare events in which mesons are created in close vicinity, leading to an avalanche of scattering events. Only at much later times a true thermal equilibrium is achieved in which the meson number conservation is violated by a mechanism akin to the Schwinger effect. The discussed prethermalization dynamics is directly relevant to generic one-dimensional, many-body systems with confined excitations