Experimental Investigations on Nonlinear Properties of Superconducting Nanowire Meanderline in RF and Microwave Frequencies

We report our experimental investigations on the radio frequency (RF) and microwave nonlinear behavior of the NbN nanowire meanderline. We construct a lumped element model of the NbN nanowire meanderline, which consists of a kinetic inductance, a normal resistance, and a parasitic capacitance that is a load of a transmission line. Two complementary measurements, which are based on the one-port scattering (S)-parameter technique, are used to explore the nonlinearity in the kinetic inductance and the normal resistance of the NbN nanowire meanderline under dc current and voltage bias conditions. In the first series of experiments, the kinetic inductance has directly been measured from zero up to 99% of the critical current and to the voltage bias, where the hotspot plateau occurs. The Ginsburg-Landau (G-L) theory has been employed to justify the results. The technical procedures required to achieve our desired level of accuracy have been described in detail. In the second series of experiments, the quality factor of the NbN nanowire meanderline has been measured, providing an alternative justification to the first experimental results.