The Josephson effects in weakly coupled superconductors

Abstract

The effects described arise as a consequence of two terms calculated by Josephson in the expression for the electrical current flowing between a pair of weakly coupled superconductors. One of these terms is present at zero voltage and represents a supercurrent which can cross such barriers as thin layers of insulator or normal metal; the other is an extra component of resistive current. The review sets out sufficient theoretical background to allow readers with no previous knowledge of superconductivity to understand the basic physics of the effects. It also caters for those wishing to learn enough to understand devices based on Josephson effects. The article concentrates on fundamentals, and early and recent experimental and theoretical developments in the understanding of Josephson weak links of all types are emphasized.