Nonequilibrium charge transport in quantum SINIS structures

TL;DR

This paper investigates charge transport in long, high-transmission SINIS junctions at low bias and temperature, revealing how Zener transitions significantly boost the dc current beyond the critical Josephson current.

Contribution

It derives a kinetic equation incorporating inelastic relaxation and Zener transitions, showing their combined effect on charge transport in long SINIS junctions.

Findings

Zener transitions enhance quasiparticle transitions in the junction.

The dc current can exceed the critical Josephson current due to these effects.

Long junctions with many levels exhibit a drastic increase in dc current.

Abstract

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 Zener transitions between the levels. We show that, for a long junction when the number of levels is large, the 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.