Localised Dynamics in the Floquet Quantum East Model

Abstract: We introduce and study the discrete-time version of the Quantum East model, an interacting quantum spin chain inspired by simple kinetically constrained models of classical glasses. Previous work has established that its continuous-time counterpart displays a disorder-free localisation transition signalled by the appearance of an exponentially large (in the volume) family of non-thermal, localised eigenstates. Here we combine analytical and numerical approaches to show that: i) The transition persists for discrete times, in fact, it is present for any finite value of the time step apart from a zero measure set; ii) It is directly detected by following the non-equilibrium dynamics of the fully polarised state. Our findings imply that the transition is currently observable in state-of-the-art platforms for digital quantum simulation.