Initial experimental results on a superconducting-qubit reset based on photon-assisted quasiparticle tunneling

We present here our recent results on qubit reset scheme based a quantum-circuit refrigerator (QCR). In particular, we use the photon-assisted quasiparticle tunneling through superconductor–insulator–normal-metal–insulator–superconductor junction to controllably decrease energy relaxation time of during QCR operation. experiment, transmon with dispersive readout. The is capacitively coupled its normal-metal island. employ rapid, square-shaped control voltage pulses durations in range 2–350 ns and variety amplitudes optimize fidelity. Consequently, reach ground-state probability roughly 97% 80-ns starting from first excited state. state extracted averaged readout signal, where calibration Rabi oscillations, thus not distinguishing residual thermal population qubit.