Observation of a Phase-Dependent Conductivity in Superconducting Point Contacts

Abstract

Measurements of the impedance of phase-biased superconducting point contacts are interpreted in terms of the Josephson expression for the total current, $i=i_{c}sin\varphi +G_0(1+\alpha \times cos\varphi )V$. The data give good agreement with this expression and yield a parametric inductance $\mathcal{L}\left(\varphi \right)=\frac{\hslash }{2e{i}_{c}cos\varphi }$ and a phase-dependent conductance $G\left(\varphi \right)=G_0(1+\alpha cos\varphi )$, with $\alpha \approx -1\mathrm{}$.