Persistent Currents in a Spin-Imbalanced Ultracold Fermi Gas in a Ring

We will present the results of experiments involving the creation and decay of persistent currents in a spin-imbalanced Fermi gas in a ring. Variations in the depth of the trapping potential generally cause accumulation of the majority spin component in shallower regions of the ring, which affects the stability of persistent currents and the response of the system to rotating perturbations. We hope to achieve conditions where a sufficiently localized repulsive potential acts as a magnetic impurity, forming a π-Josephson junction and a spontaneous current in the ground state. We will report on progress toward these goals.