Symmetry breaking dynamics in open mesoscopic quantum systems*

Atom tweezer arrays enable one to contruct and control quantum systems on the scale from single, to few, to many atoms. Among many impacts of this ability, here, we emphasize new directions in the study of matter-light interactions. In particular, we have integrated an atom array into a high-finesse optical resonator and studied the response of this atoms-cavity quantum system to external optical drive. Collective scattering by the array into the cavity, together with the response of the atoms to cavity light, leads to spontaneous self organization, both in the mechanical and in the spin degrees of freedom, closely related to the superradiant phase transition in the Dicke model. We examine this phase transition in the mesoscopic regime, e.g. with sample ranging from 10 to 22 atoms. We observe distinct features of mesoscopic physics, manifest in the temporal dynamics of spontaneous symmetry breaking and in the susceptibility to explicit symmetry breaking. I will also provide an update on other branches of our atom-array/optical cavity research.