Combined effect of Zener and quasiparticle transitions on the dynamics of mesoscopic Josephson junctions

Abstract

We study ultrasmall Josephson junctions using the coherent picture to describe the pair dynamics and the semiclassical approach for the quasiparticles. We find that the dynamics depends crucially on the ratio of the superconducting gap energy Δ(T) to the charging energy ${\mathrm{e}}^2$/2C. The pair ‘‘Bloch oscillations’’ can be practically observed when 2Δ(T)>${\mathrm{e}}^2$/2C; for 2Δ(T)${\mathrm{e}}^2$/2C the ${\mathrm{I}}_{\mathrm{dc}/\mathrm{e}}$ oscillations due to quasiparticle tunneling can be observed. We discuss under what conditions the I-V characteristic will be S-shaped, exhibiting both oscillations at different values of the current.