Weak ergodicity breaking in the Schwinger model

As a paradigm of weak ergodicity breaking in disorder-free nonintegrable models, quantum many-body scars (QMBS) can offer deep insights into the thermalization dynamics of gauge theories. Having been first discovered in a spin -21 quantum link formulation of the Schwinger model, it is a fundamental question as to whether QMBS persist for S > 12 since such theories converge to the lattice Schwinger model in the large -S limit, which is the appropriate version of lattice QED in one spatial dimension. In this work, we address this question by exploring QMBS in spin -S U(1) quantum link models (QLMs) with staggered fermions. We find that QMBS persist at S > 12, with the resonant scarring regime, which occurs for a zero-mass quench, arising from simple high-energy gauge-invariant initial product states. We furthermore find evidence of detuned scarring regimes, which occur for finite-mass quenches starting in the physical vacua and the charge-proliferated state. Our results conclusively show that QMBS exist in a wide class of lattice gauge theories in one spatial dimension represented by spin -S QLMs coupled to dynamical fermions, and our findings can be tested on near-term cold-atom quantum simulators of these models.