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

Single-shot readout of a quantum state is an essential component in building a large-scale quantum processor, and reducing the readout error is the key challenge. To achieve a high signal-to-noise ratio, quantum-limited low-noise amplifiers such as Josephson parametric amplifiers are typically used. However, a high-fidelity 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-multiplexed, 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 used in tomography of an entangled state. We have demonstrated the potential usefulness of this technique in characterizing the final quantum state at the end of quantum operations in a superconducting quantum processor.