Investigating nonlinearity in Sn–InAs nanowire-based Josephson parametric amplifiers

Josephson parametric amplifiers (JPAs) are essential first-stage amplifiers for high-fidelity measurement of weak cryogenic microwave signals. Beyond amplification, JPA circuits offer a versatile platform to explore potentially richer nonlinear behavior in hybrid, proximitized semiconducting Josephson junctions, where strong spin–orbit coupling and finite magnetic fields can give rise to higher-order or odd-order nonlinear responses not typically accessible in conventional tunnel junctions without complex circuit engineering. In this work, single Sn-InAs nanowire Josephson junctions exhibiting supercurrents on the order of 0.5 µA, have been incorporated in NbTiN co-planar waveguide resonators and measured in reflection. The intrinsic quartic nonlinearity of the junction enables a four-wave mixing process that yields up to 20 dB of parametric gain. The effect of gate tunability (observed on the order of hundreds of MHz) and magnetic field on the amplifier’s performance and nonlinearity are also being investigated.