Subharmonic stabilization of quantum many-body scars in Rydberg atom arrays*

Understanding and controlling quantum entanglement dynamics in many-body systems away from equilibrium is an outstanding challenge. In complex systems, such dynamics typically leads to chaotic spreading throughout the Hilbert space associated with thermalization. Using a programmable quantum simulator based on Rydberg atom arrays in one and two dimensions, we experimentally investigate dynamics resulting from rapid quenches across quantum phase transitions. For specific initial states on a wide variety of bipartite lattices, we observe collapses and revivals of the order parameters, corresponding to quantum many-body scars, and explore their thermalization mechanisms. Remarkably, we discover that scar revivals can be stabilized by applying a periodic drive, which further locks the scar oscillation frequency to half the drive frequency. We map phase diagrams of this subharmonic response and show its robustness increases with system size, akin to time crystalline behavior. These observations challenge understandings of quantum thermalization and allow for steering entanglement growth in many-body systems. I will also showcase other recent efforts on quantum simulation of 2D phases and quantum optimization.