Emergent symmetries and slow quantum dynamics in a Rydberg chain with confinement

Rydberg atoms in optical tweezer arrays provide a playground for nonequilibrium quantum many-body physics. The PXP model describes the dynamics of such systems in the strongly interacting Rydberg blockade regime and notably exhibits weakly nonergodic dynamics due to quantum many-body scars. Here, we study the PXP model in a strong staggered external field, which has been proposed to manifest quasiparticle confinement in light of a mapping to a lattice gauge theory. We characterize this confining regime using both numerical exact diagonalization and perturbation theory around the strong-field limit. In addition to the expected emergent symmetry generated by the staggered field, we find a second emergent symmetry that is special to the PXP model. The interplay between these emergent symmetries and the Rydberg blockade constraint dramatically slows down the system's quench dynamics beyond what is found in other systems with confinement. We devise a nested Schrieffer-Wolff perturbation theory to derive the effective Hamiltonian with both emergent symmetries and show that this treatment is essential to understand the numerically observed relaxation timescales under quantum quenches from initial product states.