Accurate Determination of the Josephson Critical Current by Lock-In Measurements

Operation of Josephson electronics usually requires determination of the Josephson critical current [Formula: see text] , which is affected both by fluctuations and measurement noise. Lock-in measurements allow obviation of [Formula: see text] noise, and therefore, provide a major advantage in terms of noise and accuracy with respect to conventional dc measurements. In this work we show both theoretically and experimentally that the [Formula: see text] can be accurately extracted using first and third harmonic lock-in measurements of junction resistance. We derived analytical expressions and verified them experimentally on nano-scale Nb–PtNi–Nb and Nb–CuNi–Nb Josephson junctions.