High-frequency parametric amplification leveraging kinetic inductance of WSi

Parametric amplifiers used for superconducting circuit readout are conventionally designed to operate in the C-band (4-8 GHz) for compatibility with microwave components. However, for dispersive qubit readout, this limits the maximum detuning between the qubit and the cavity to a few gigahertz, introducing unwanted transitions to levels outside the computational basis. Moving the readout cavity to the Ka-band (25-40 GHz) has been proposed to mitigate measurement induced state transitions, allowing for higher readout powers. However, there are few parametric amplifiers in this frequency range. In this context, we investigate kinetic inductance-based amplifiers as they have excellent scaling to high frequency. We use WSi for its low critical current reducing the pump power requirements relative to other KI materials while maintaining high power handling. We characterize the internal losses and nonlinear response of WSi resonators in the C and Ka-bands and show that the material is well suited for parametric amplification. We then present a waveguide-integrated, resonant-based, amplifier operating in the Ka-band, followed by early designs for a travelling-wave parametric amplifier employing a novel phase matching feature which exploits the natural high impedance nature of kinetic inductance.