SCATTERING-THEORY OF SUPERCONDUCTIVE TUNNELING IN QUANTUM JUNCTIONS

A consistent theory of superconductive tunneling in single-mode juncti ons within a scattering formulation of Bogolyubov-de Gennes quantum me chanics is presented. The de Josephson effect and the de quasiparticle transport in the voltage-biased junctions are considered. Elastic qua siparticle scattering by the junction determines the equilibrium Josep hson current. The origin of Andreev bound states in tunnel junctions a nd their role in equilibrium Josephson transport are discussed, in con trast, quasiparticle tunneling in voltage-biased junctions is determin ed by inelastic scattering. A general expression for inelastic scatter ing amplitudes is derived and the quasiparticle current is calculated at all voltages with emphasis on a discussion of the properties of sub gap tunnel current and the nature of subharmonic gap structure. (C) 19 97 American Institute of Physics.