Observability of Quasiparticle-Pair Interference Current in Superconducting Weak Links

Calculations of static $I_0-V_0$ curves, and of the heights of steps induced by rf radiation, have been carried out for current-biased Josephson junctions with both a phase-independent quasiparticle conductance $G_0$ and a phase-dependent quasiparticle pair "interference" conductance $G_{1}cos\phi$. Little or no effect of the term in $G_{1}cos\phi$ is found for junctions with zero capacitance. It thus appears that this term can be neglected in many practical applications of weak links. Substantial effects are found for the case of finite junction capacitance. The term in $G_{1}cos\phi$ then enhances the hysteresis of the static $I_0-V_0$ curve by an amount which roughly corresponds to a factor of 2-5 increase in capacitance, and causes the static voltage to increase above the value expected from the shunt conductance alone. The most easily observable effect of the term in $G_{1}cos\phi$ on the rf-induced step heights is a pronounced shift in the values of rf current for which maxima occur for low values of normalized rf frequency.