Saturated Collisional Resistivity in Ultracold Hubbard Metals
Joseph Thywissen (University of Toronto, Canada)
Optical lattices provide clean periodic potentials for ultracold neutral fermions. Without phonons or impurity scattering, finite resistivity arises solely from interactions among itinerant atoms. We investigate this mechanism in a cubic lattice with tunable s-wave interactions and variable temperature. In the strongly interacting metallic regime, we observe a striking saturation of the current relaxation rate towards a value that is independent of the interaction strength. Is this the signature of "lattice unitarity"? By comparison to a resistivity calculation that uses a renormalized two-body scattering matrix, we benchmark a kinetic model of this Hubbard metal and find that the unitary bound is not reached, even in the limit of infinite scattering length.Â