Temperature and magnetic field variations in the resistance,cos ϕ conductance,and effective capacitance of small Josephson junctions

From direct microwave reflection measurements on very small Pb Josephson junctions, we found a previously unobserved maximum in the small voltage tunneling resistance as the temperature was lowered just below the superconducting transition temperature. In the same range the cos ? amplitude increased to + 1 and then rapidly decreased to ? 1. The effective junction capacitance increased 2–3 times when the magnetic field (for tuning the plasma resonance) was increased, which can be interpreted as evidence for the existence of a phase dependent parametric capacitance.