Stages of the Excitation Relaxation in a Superconductor after the Impact of a Femtosecond Laser Pulse Taking into Account the Momentum Distribution of Quasiparticles

摘要： A theoretical model is formulated for the description of the nonequilibrium state of a superconductor on the basis of the nonequilibrium distribution function of phonons and quasiparticles on a finite momentum lattice convenient for numerical simulation. The simulation is performed under conditions of pulsed optical impact demonstrating the role of excess quasiparticles in suppressing the order parameter and the main stages of the relaxation process in the absence of electric current.