Application of a broadband Josephson parametric amplifier
We examine the performance of a Josephson Parametric Amplifier (JPA) which uses an array of SNAILs (Superconducting Nonlinear Asymmetric Inductive eLements) as the source of nonlinearity and leverages the technique of impedance engineering (introducing a positive linear slope in the imaginary part of the input impedance seen by the SNAILs) to overcome a traditional gain-bandwidth product and increase the 1-dB compression point. We experimentally demonstrate an 18 dB gain over a 586 MHz band, along with a 1-dB compression point -101.9 dBm. All these characteristics are of great importance for the quantum devices measurements and in particular for the single-shot readout of a multi-qubit system. The signal-to-noise ratio after the application of the JPA was increased by 3 times. That led to the improvement of separation fidelity of single-shot dispersive measurements of a transmon qubit from 30.6% to 97.2%.