Constructing Quantum Many-Body Scars from Hilbert Space Fragmentation

TL;DR

This paper presents a scalable method to construct quantum many-body scars in kinetically constrained models, linking Hilbert space fragmentation to non-thermal states, with potential implementation in neutral-atom quantum simulators.

Contribution

It introduces a simple, scalable construction of QMBS from Hilbert space fragmentation, connecting these states to lattice quasiparticles and inelastic collisions.

Findings

Exact QMBS constructed via quasiparticle injection

Approximate scars formed through quasiparticle collisions

Model suitable for implementation in neutral-atom quantum simulators

Abstract

Quantum many-body scars (QMBS) are exotic many-body states that exhibit anomalous non-thermal behavior in an otherwise ergodic system. In this work, we demonstrate a simple, scalable and intuitive construction of QMBS in a kinetically constrained quantum model exhibiting weak Hilbert space fragmentation. We show that exact QMBS can be constructed by injecting a quasiparticle that partially activates the frozen regions in the lattice. Meanwhile, the inelastic collision between multiple quasiparticles allows for the construction of approximate scars, whose damping is governed by an emergent two-body loss. Our findings establish direct connections between quantum many-body scarring and Hilbert space fragmentation, paving the way for systematically constructing exact and approximate QMBS with nontrivial spatial connectivity. The proposed model can be readily implemented in neutral-atom quantum simulators aided by strong Rydberg interactions.