Superconducting Qubit Readout with a Kinetic Inductance Traveling-wave Parametric Amplifier

In this talk we discuss the wideband gain and noise temperature characterization of a kinetic inductance traveling-wave (KIT) amplifier and its use for the simultaneous readout of multiple superconducting transmon qubits. The amplifier consists of a long nonlinear NbTiN superconducting coplanar waveguide parametrically driven by injecting a strong microwave pump to modulate the line kinetic inductance. The amplifier provides wideband gain in the 4-12 GHz band, high saturation power and low noise. We measured the calibrated gain, return loss and noise temperature data over the entire device bandwidth using a combination of thru-reflect-line calibration standards and a tunable temperature load. Furthermore we performed the simultaneous single-shot readout of two superconducting transmon qubits and amplified the corresponding readout tones with the KIT amplifier, obtaining greater than 90% readout fidelity.