Non-equilibrium fluctuations and metastability in the dynamics of dissipative multi-component Rydberg gases

We study out-of-equilibrium dissipative gases of atoms excited to multiple high-lying atomic levels. The relative strength of the intra-level and the inter-level interactions has great implications for the emerging phenomenology. When the inter-level interactions are dominant the dynamics is characterized by homogeneous domain formation, while stronger intra-level interactions lead to heterogeneous domains with an alternating arrangement of excitations. Such patterns dominate throughout the non-equilibrium evolution of the system, but they eventually subside into the fully de-correlated stationary state. Before this happens partial equilibrium occurs within each domain, leading to a metastable dynamics that may persist for long times. In experimental settings, where the lifetimes and the system sizes are finite, these metastable states may take the appearance of dynamic symmetry breaking.