Quantum Efficient Measurement of a Transmon via a High Saturation Power Josephson Parametric Amplifier Part 1

High-fidelity quantum non-demolition qubit measurement is critical to error correction and feedback in large-scale quantum computing. High-fidelity readout requires a short and strong pulse transiting the qubit's measurement mode which is then processed by a necessarily high bandwidth, high saturation power, quantum-limited amplifier. In this talk, we present the design and fabrication of a single-mode amplifier which meets these criteria. The amplifier utilizes an array of 25 radio frequency Superconducting QUantum Interference Devices (rf-SQUIDS) embedded within a low-Q resonator powered by a high-power voltage pump delivered via a diplexer on the signal port. We show that despite the intensity of the pump, the device is quantum-efficient and capable of high-fidelity measurement limited by state transitions in the transmon. We will present experimental data demonstrating -90dBm input saturation power with 20dB gain over 50MHz and phase preserving qubit measurements with > 60 % quantum efficiency.