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

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. Some quantum spin models provide a condensed-matter realization of confinement, and previous work has shown that confinement affects the way they thermalize. Here the authors demonstrate for a many-body model with confinement that thermalization dynamics occurs in multiple stages, starting with a prethermal state.

Automated summary

This study investigates the thermalization dynamics after a quantum quench in confined systems and finds that it exhibits multiple stages. Taking the confined Ising spin chain as an example, bound states resembling mesons are formed. The system first reaches a prethermal state related to the number of conserved mesons, and then achieves true thermal equilibrium at much later times.