Two-particle tunnelling between superconductors

摘要: Abstract Excess currents have been observed in electron tunnelling between superconductors which cannot be explained on a model assuming the of single particles. They take form current step at applied voltages equal to half energy gap either superconductor, followed by an exponential-like rise current. The size varies greatly samples and is sometimes too small detect, but it typically 10−4 normal state same voltage. excess are attributed processes two particles tunnel simultaneously through insulating barrier (Schrieffer Wilkins 1963). conditions for occurrence various examined, higher-order discussed.