Current-carrying states in Josephson junctions

Abstract

A unified treatment of clean Josephson junctions—both tunnel junctions and weak links—is developed for the static case. The quasiparticle local density of states in Josephson junctions is calculated, and it is found that the energy spectrum depends strongly on the phase difference between the two superconductors. In the case of tunnel junctions, it is predicted that bound states which are localized around the tunnel barrier appear in the energy gap. The Josephson current flows via the bound states. The possibility to observe such current-carrying states by scanning tunneling spectroscopy is discussed.