Saturation of Current Dissipation in the Fermi-Hubbard Model

The Fermi-Hubbard model describes a rich variety of physical phenomena in condensed matter systems. Ultracold atom quantum simulators provide a near-ideal testbed as they are highly tunable and relatively defect-free. We probe dissipation in the driven 3D Fermi-Hubbard model by measuring the AC conductivity spectrum in response to an oscillatory force provided by a periodically displaced optical potential. Conductivity is extracted by measuring the atom displacement via in-situ imaging with a quantum gas microscope. Effects of atom-atom collisions on the current dissipation are explored by tuning the interaction strength via a Feshbach resonance. By operating sufficiently close to the resonance, we enter a non-perturbative regime in interaction strength where the dissipation is expected to be limited by the tunneling rate. We observe a predicted saturation of current dissipation rate with increasing interaction strength. Results are compared to a Boltzmann transport model.