The Proximity and Josephson Effects

Abstract

Suppose one superconductor is separated from another by a thin layer of insulator, then such a S₁–I–S₂ junction is called a weak-link or a Josephson junction. The Cooper pairs can tunnel across the narrow insulator from one superconductor to the other superconductor. The effects of pair tunnelling are classified under two categories: DC Josephson effects: A dc current flows across the junction in the absence of any electric or magnetic field. AC Josephson effects: A dc voltage applied across the junction causes rf current oscillations across the junction. Further, an rf voltage applied with the dc voltage can cause a dc current across the junction.