# Emergent SU(2) dynamics and perfect quantum many-body scars

## TL;DR

This paper demonstrates how a weak deformation of the Rydberg Hamiltonian can produce near-perfect quantum many-body revivals by supporting emergent SU(2) dynamics and nonergodic scar states, advancing understanding of quantum scars.

## Contribution

It introduces a weak quasi-local deformation that enhances revivals and reveals an emergent SU(2) structure supporting quantum many-body scars, along with a toy model illustrating their origin.

## Key findings

- Deformation makes revivals nearly perfect.
- Emergent SU(2) dynamics underpins scar states.
- Constructed a toy model with exact scars.

## Abstract

Motivated by recent experimental observations of coherent many-body revivals in a constrained Rydberg atom chain, we construct a weak quasi-local deformation of the Rydberg blockade Hamiltonian, which makes the revivals virtually perfect. Our analysis suggests the existence of an underlying non-integrable Hamiltonian which supports an emergent SU(2)-spin dynamics within a small subspace of the many-body Hilbert space. We show that such perfect dynamics necessitates the existence of atypical, nonergodic energy eigenstates - quantum many-body scars. Furthermore, using these insights, we construct a toy model that hosts exact quantum many-body scars, providing an intuitive explanation of their origin. Our results offer specific routes to enhancing coherent many-body revivals, and provide a step towards establishing the stability of quantum many-body scars in the thermodynamic limit.