Rainbow Scars: From Area to Volume Law

TL;DR

This paper introduces a generic construction of rainbow quantum many-body scars that exhibit volume-law entanglement in Hamiltonians, including translation-invariant models, and proposes an experimental realization in Rydberg-atom systems.

Contribution

It develops a universal method to embed rainbow scars into arbitrary Hamiltonians, expanding the understanding of ergodicity breaking in quantum many-body systems.

Findings

Rainbow scars display volume-law entanglement for random bipartitions.

Multiple towers of rainbow scars can exist with internal symmetries.

Experimental realization in Rydberg-atom systems shows distinct coherent oscillations.

Abstract

Quantum many-body scars (QMBS) constitute a new quantum dynamical regime in which rare "scarred" eigenstates mediate weak ergodicity breaking. One open question is to understand the most general setting in which these states arise. In this work, we develop a generic construction that embeds a new class of QMBS, rainbow scars, into the spectrum of an arbitrary Hamiltonian. Unlike other examples of QMBS, rainbow scars display extensive bipartite entanglement entropy while retaining a simple entanglement structure. Specifically, the entanglement scaling is volume-law for a random bipartition, while scaling for a fine-tuned bipartition is sub-extensive. When internal symmetries are present, the construction leads to multiple, and even towers of rainbow scars revealed through distinctive non-thermal dynamics. Remarkably, certain symmetries can lead rainbow scars to arise in translation-invariant models. To this end, we provide an experimental road map for realizing rainbow scar states in a Rydberg-atom quantum simulator, leading to coherent oscillations distinct from the strictly sub-volume-law QMBS previously realized in the same system.