Quantum scars of bosons with correlated hopping

Recent experiments on Rydberg atom arrays have found evidence of anomalously slow thermalization and persistent density oscillations, which have been interpreted as a many-body analog of the phenomenon of quantum scars. Periodic dynamics and atypical scarred eigenstates originate from a “hard” kinetic constraint: the neighboring Rydberg atoms cannot be simultaneously excited. Here we propose a realization of quantum many-body scars in a 1D bosonic lattice model with a “soft” constraint in the form of density-assisted hopping. We discuss the relation of this model to the standard Bose-Hubbard model and possible experimental realizations using ultracold atoms. We find that this model exhibits similar phenomenology to the Rydberg atom chain, including weakly entangled eigenstates at high energy densities and the presence of a large number of exact zero energy states, with distinct algebraic structure. Quantum many-body scarring, a peculiar phenomenon whereby a system thermalizes whilst it keeps returning to its initial state during the time evolution, has recently been observed in experiments on arrays of Rydberg atoms. The authors theoretically investigate the spectral properties of three Hamiltonians using a chain of bosons with density-dependent hopping, providing new insight in the phenomenon of many-body quantum scarring.