Properties of Nonequilibrium Superconductors: A Kinetic Equation Approach
Within the frame work of the BCS theory of superconductivity (Bardeen et al. 1957), a superconductor is a system of three components: The quasiparticles, the phonons, and the paired electrons. In this chapter, we will discuss some of the nonequilibrium properties of superconductors using the kinetic-equation approach. The quasiparticles and phonons will be described by coupled kinetic equations which govern the quasiparticle and phonon distribution functions. The paired electrons are characterized by the energy gap which will be described by a modified gap equation relating the energy gap to the energy spectrum of the quasiparticles. We will use the Golden-Rule approximation in our derivation of the kinetic equations. This approach is simple and brings out clearly the physics involved in the various collision processes. Furthermore, it has been shown that, for all practical purposes, it is equivalent to the more rigorous Green’s function approach (Eliashberg, 1970; Entin-Wohlman and Orbach, 1978).
KeywordsTunneling Process Quasi Particle Phonon Distribution Sharp Structure Quasiparticle Density
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