The Josephson tunneling through an interacting quantum dot

Alex Rozhkov

Abstract

It has been known for some time that a Josephson contact through an Anderson impurity has negative critical current $J_c < 0$. Such system is commonly reffered to as $\pi$-junction. In my talk I will discuss different examples of the Josephson devices. All of them, however, share the same quality: the Cooper pairs tunnel through an interacting quantum dot. I will show that the Coulomb repulsion on the dot may force $J_c$ to be negative. It can also lead to another exotic situation when the Josephson current is a discontinuos function of the phase difference.