Kinetics of interacting quasiparticles and phonons in non-equilibrium superconductors

We have found an analytical solution for the energy down-conversion process in the system of interacting quasiparticles (qps) and phonons in non-equilibrium superconductor following the absorption of an energetic photon. The electron–phonon down-conversion stage is shown to split into two phases. In the first the energy of the initial quantum evolves mainly through the distribution of phonons while during the second phase it converts into the energy of qps. Depending on the material parameters the contributions from phonon and qp phases are different resulting in distinctive features of qp generation rates.