Interaction-controlled transport of an ultracold Fermi gas

We explore the transport properties of an interacting Fermi gas in a three-dimensional optical lattice. In analogy to the characterization of transport behavior in condensed matter systems through conductivity measurements, we study the atom cloud's center of mass motion after a sudden displacement of the trap minimum. Different interaction strengths and lattice fillings are shown to have a characteristic influence on the dynamics. With increasingly strong attractive interactions the weakly damped oscillation, observed for the non-interacting case, turns into a slow drift: local pairs with a reduced tunneling rate are formed for strong inter-atomic attraction. Application of this technique in other interaction regimes, lattice depths and fillings in the Fermi-Hubbard model may provide a tool for the identification of quantum phases such as the fermionic Mott-insulator. Experimental results on repulsively interacting Fermi gases will be presented.