Correspondence Principle for Many-Body Scars in Ultracold Rydberg Atoms

The theory of quantum scarring -- a remarkable violation unique ergodicity rests on two complementary pillars: the existence unstable classical periodic orbits and so-called quasimodes, i.e., non-ergodic states that strongly overlap with small number system's eigenstates. Recently, interest in scars has been revived many-body setting Rydberg atom chains. While previous theoretical works have identified for such systems using time-dependent variational principle (TDVP), link between quasimodes missing. Here we provide conceptually simple analytic construction non-integrable model, prove they arise from "requantisation" previously established when fluctuations are restored to all orders. Our results shed light TDVP system simultaneously playing role both mean-field approximation limit, thus allowing us firm up analogy eigenstate chains single-particle systems.