Nonequilibrium effects in tunnel Josephson junctions

Artikel i vetenskaplig tidskrift, 2005

We study nonequilibrium effects in current transport through voltage biased tunnel junction with long diffusive superconducting leads at low applied voltage eV 2Δ, and finite temperatures. Due to a small value of the Josephson frequency, the quasiparticle spectrum adiabatically follows the time evolution of the superconducting phase difference, which results in the formation of oscillating bound states in the vicinity of the tunnel junction (Andreev band). The quasiparticles trapped by the Andreev band generate higher even harmonics of the. Josephson ac current, and also, in the presence of inelastic scattering, a nonequilibrium dc current, which may considerably exceed the dc quasiparticle current given by the tunnel model. The distribution of traveling quasiparticles also deviates from the equilibrium due to the spectrum oscillations, which results in an additional contribution to the dc current, proportional to V.