Unconventional many-body scarring in a Bose--Hubbard quantum simulator

Quantum many-body scarring presents a novel mechanism that delays the onset of thermal equilibrium in non-integrable models. Using a large-scale Bose--Hubbard quantum simulator, we realize many-body scarring by emulating the PXP model with the tilted optical lattice and subsequently extending the scarring phenomenon to an unconventional regime in the unity-filling state. We demonstrate the combination of detuning and periodic driving deters the scrambling of initial state information by measuring the quantum fidelity of single-site subsystems with many-body interference in a superlattice. The interference protocol also helps read out single-site entanglement entropy, which further illustrates the trapping of the many-body system in a low-entropy subspace. Our work paves the way for investigating many-body scars in ultracold-atom experiments and exploring its relation to lattice gauge theories, Hilbert space fragmentation, and disorder-free localization.