Nonequilibrium quasiparticle distribution function and the thermal regime of laser-irradiated tunnel junctions

We have investigated the decrease of the lead tunnel junction conductivity at eV≳2Δ under nonequilibrium conditions. The effects of temperature, irradiation intensity, method of excitation, and heat transfer regime on the nonequilibrium quasiparticle distribution function were studied in detail. The comparison of experimental results with calculations makes it possible to reach conclusions concerning the form of the nonequilibrium quasiparticle distribution function, and about the nature of the observed effect.