Optical superlattice for engineering Hubbard couplings in quantum simulation

Quantum simulations of Hubbard models with ultracold atoms rely on the exceptional control of coherent motion provided by optical lattices. Here we demonstrate enhanced tunability using an optical superlattice in a fermionic quantum gas microscope. With our phase-stable bichromatic design, we achieve a precise control of tunneling and tilt throughout the lattice, as evidenced by long-lived coherent double-well oscillations and next-nearest-neighbor quantum walks in a staggered configuration. We furthermore present correlated quantum walks of two particles initiated through a resonant pair-breaking mechanism. Finally, we engineer tunable spin couplings through local offsets and create a spin ladder with ferromagnetic and antiferromagnetic couplings along the rungs and legs, respectively. Our work underscores the high potential of optical superlattices for engineering, simulating, and detecting strongly correlated many-body quantum states.