Nonadiabatic Pumping through Interacting Quantum Dots

We study nonadiabatic two-parameter charge and spin pumping through a single-level quantum dot with Coulomb interaction. For the limit of weak tunnel coupling and in the regime of pumping frequencies up to the tunneling rates, Omega less than or similar to Gamma/(h) over bar, we perform an exact resummation of contributions of all orders in the pumping frequency. As striking nonadiabatic signatures, we find frequency-dependent phase shifts in the charge and spin currents, which opens the possibility to control charge and spin currents by tuning the pumping frequency. This includes the realization of an effective single-parameter pumping as well as pure spin without charge currents.