Kinetic theory of resistive states and electric oscillations in superconducting channels

Abstract

The nature of resistive current states in a narrow superconducting channel at temperatures close to critical is discussed on the basis of the quantum kinetic theory for a generalized electron-hole density matrix. A new physical aspect of superconductivity is revealed: The superconductor displays peculiar properties in response to a nonequilibrium longitudinal electric field in the presence of a coherent source of electrons—a superconducting condensate. The microscopic structure of resistive states consists of a periodic alternation, along the uniform channel, of “normal” and “superconducting” regions described by singular solutions of the mean field equations. The singularities come from the discontinuity of the time derivative of the phase of the superconducting order parameter (“phase slip”) and provide “voltage units” through which the longitudinal electric field penetrates into the channel. In the paperI–V curves for resistive states are calculated and some nonstationary phenomena are pointed out.