Quantum many-body scars: connections to integrability and stability

Quantum many-body scar states are exceptional finite energy density eigenstates in an otherwise thermalizing system that do not satisfy the eigenstate thermalization hypothesis. Recent atomic array experiments in the Rydberg blockaded regime suggests that the simplest blockaded Hamiltonian, the PXP Hamiltonian, has such scars in its spectrum. In this talk, I will discuss the connections between integrability and quantum scars by identifying a proximate integrable point at which the non-thermal signatures of the scar states become more pronounced. I will further discuss the stability of quantum scars to generic perturbations. Although the scar states hybridize with the other states in the spectrum upon perturbation, their nonthermal properties survive for a parametrically long time in quench experiments.