Scar States in Deconfined $\mathbb{Z}_2$ Lattice Gauge Theories

TL;DR

This paper demonstrates the existence of quantum many-body scar states in a lattice gauge theory, specifically in the gauged Kitaev model, revealing non-ergodic behavior due to local constraints even in deconfined regimes.

Contribution

It uncovers quantum many-body scars in a lattice gauge theory with local constraints, expanding understanding of non-ergodic dynamics beyond integrable regimes.

Findings

Scar states exist far from integrability in the gauged Kitaev model.

Persistent oscillations observed in quantum quenches from specific initial states.

Scar states linked to local constraints and extensive degeneracies.

Abstract

The weak ergodicity breaking induced by quantum many-body scars (QMBS) represents an intriguing concept that has received great attention in recent years due to its relation to unusual non-equilibrium behaviour. Here we reveal that this phenomenon can occur in a previously unexplored regime of a lattice gauge theory, where QMBS emerge due to the presence of an extensive number of local constraints. In particular, by analyzing the gauged Kitaev model, we provide an example where QMBS appear in a regime where charges are deconfined. By means of both numerical and analytical approaches, we find a variety of scarred states far away from the regime where the model is integrable. The presence of these states is revealed both by tracing them directly from the analytically reachable limit, as well as by quantum quenches showing persistent oscillations for specific initial states.