Universality and weak-ergodicity breaking in quantum quenches

TL;DR

This paper explores how lattice discretization causes weak ergodicity breaking in quantum many-body systems after quenches, clarifying previous conflicting results on universal scaling and equilibration.

Contribution

It demonstrates that lattice effects are responsible for weak ergodicity breaking and resolves contradictions in quantum $O(n)$ models' behavior post-quench.

Findings

Lattice discretization induces weak ergodicity breaking.

Reconciliation of universal scaling and equilibration results.

Clarification of lattice effects on quantum $O(n)$ models.

Abstract

Sudden quenches in quantum many-body systems often lead to dynamical evolutions that unveil surprising physical behaviors. In this work, we argue that the emergence of weak ergodicity breaking following quantum quenches in certain local many-body systems is a direct consequence of lattice discretization. To support this claim, we investigate the out-of-equilibrium dynamics of quantum $O(n)$ models on a lattice. In doing so, we also revisit two puzzling results in the literature on quantum $O(n)$ models, concerning universal scaling and equilibration, and demonstrate how these apparent contradictions can be resolved by properly accounting for lattice effects.