Non-Equilibrium Josephson and Andreev Current through Interacting Quantum Dots

Abstract

We present a theory of transport through interacting quantum dots coupled to normal and superconducting leads in the limit of weak tunnel coupling. A Josephson current between two superconducting leads, carried by first-order tunnel processes, can be established by non-equilibrium proximity effect. Both Andreev and Josephson current is suppressed for bias voltages below a threshold set by the Coulomb charging energy. A $\pi$-transition of the supercurrent can be driven by tuning gate or bias voltages.