Nonequilibrium charge transport in quantum SINIS structures

Charge transport in a high-transmission single-mode long SINIS junction (S stands for superconductor, I is an insulator, and N is a normal metal) is considered in the limit of low bias voltages and low temperatures. The kinetic equation for the quasiparticle distribution on the Andreev levels is derived, taking into account both inelastic relaxation and voltage-driven Landau-Zener transitions between the levels. We show that, for a long junction when the number of levels is large, the Landau-Zener transitions enhance the action of each other and lead to a drastic increase of the dc current far above the critical Josephson current of the junction.