Orthogonal Quantum Many-Body Scars.

Hongzheng Zhao,Johannes Knolle,Adam Smith,Florian Mintert

doi:10.1103/physrevlett.127.150601

Abstract

Quantum many-body scars have been put forward as counterexamples to the eigenstate thermalization hypothesis. These atypical states are observed in a range of correlated models as long-lived oscillations of local observables in quench experiments starting from selected initial states. The long-time memory is a manifestation of quantum nonergodicity generally linked to a subextensive generation of entanglement entropy, the latter of which is widely used as a diagnostic for identifying quantum many-body scars numerically as low entanglement outliers. Here we show that by adding kinetic constraints to a fractionalized orthogonal metal, we can construct a minimal model with orthogonal quantum many-body scars leading to persistent oscillations with infinite lifetime coexisting with rapid volume-law entanglement generation. Our example provides new insights into the link between quantum ergodicity and many-body entanglement while opening new avenues for exotic nonequilibrium dynamics in strongly correlated multicomponent quantum systems.

Highlights

It came as a surprise when a Rydberg atom experiment reported the breaking of ergodicity in a clean and nonintegrable system as observed via long-lived oscillations after quenching from specific initial states [6]
In the Rydberg experiment, simple product states were chosen as initial states which have substantial overlap with the scar states, leading to persistent oscillations and low entanglement generation [28]
We address the intriguing question of whether long-lived coherent oscillations can coexist with rapid volume-law entanglement generation in a standard quench-setup of a clean non-integrable quantum manybody system? The intuitive answer should be No because within the Eigenstate Thermalization Hypothesis (ETH) paradigm volume-law entanglement normally goes hand-in-hand with thermal relaxation of local observables in static quantum many body systems

Summary

Introduction

It came as a surprise when a Rydberg atom experiment reported the breaking of ergodicity in a clean and nonintegrable system as observed via long-lived oscillations after quenching from specific initial states [6]. In the Rydberg experiment, simple product states were chosen as initial states which have substantial overlap with the scar states, leading to persistent oscillations and low entanglement generation [28]. We address the intriguing question of whether long-lived coherent oscillations can coexist with rapid volume-law entanglement generation in a standard quench-setup of a clean non-integrable quantum manybody system?

Results

Conclusion