High-Fidelity Multiplexed Single-Shot Readout for Transmon Qubits With High-Power Measurement

Abstract

Single-shot readout of a quantum state is an essential component in building a large-scale quantum processor, andreduc-ing the readout error is the key challenge. To achieve a high signal-to-noiseratio,quantum-limitedlow-noiseamplifierssuchasJoseph-son parametric amplifiers are typically used. However, a high-fidel-ity single-shot readout method without a parametric amplifier would be advantageous, as it would reduce system complexity. In this paper, we present a high-fidelity result of frequency-multi-plexed, high-power single-shot readout for superconducting qubits without using a parametric amplifier. We achieved a high readout fidelity of 98.3 % with a 400 ns pulse and confirmed that the high-power readout can be usedintomography of anentangledstate. We havedemonstratedthepotentialusefulnessofthistechniqueinchar-acterizing the final quantum state at the end of quantum opera-tions in a superconducting quantum processor.