Lieb-Robinson bound for constrained many-body localization

TL;DR

This paper establishes a new Lieb-Robinson bound for constrained many-body localization, revealing unique dynamical properties and nonergodic behavior in strongly interacting quantum systems, distinct from traditional localization regimes.

Contribution

It introduces a novel Lieb-Robinson bound for constrained MBL, expanding understanding of quantum information propagation in strongly interacting systems.

Findings

Discovered a new Lieb-Robinson bound for constrained MBL.

Constrained MBL exhibits nonergodic dynamics beyond local integrals of motion.

Hierarchical relationship among constrained, unconstrained, and diagonal MBL regimes.

Abstract

Study how quantum information propagates through spacetime manifold provides a means of identifying, distinguishing, and classifying novel phases of matter fertilized by many-body effects in strongly interacting systems in and out of equilibrium. Via a fuller characterization of key aspects regarding dynamic behaviors of information, we perform such an analysis on constrained many-body localization -- a newly proposed fully localized state under infinite-interaction limit -- in quasirandom Rydberg blockade spin chain models using thermal out-of-time-order commutators (OTOCs). The OTOC light cones predict a hitherto unknown Lieb-Robinson bound for constrained many-body localization, which is qualitatively different from that of unconstrained many-body Anderson insulators stabilized at weak-interaction limit. Our corroborated numeric and analytic study suggests that constrained many-body localization is a distinct dynamical eigenstate phase whose nonergodicity is beyond local-integral-of-motion phenomenology. Together, these findings consolidate the hierarchy of unconventional quantum dynamics encompassing constrained, unconstrained, and diagonal many-body-localized regimes.