Fast, high-fidelity, and low back-action readout plays a crucial role in the advancement of quantum error correction (QEC). Here, we demonstrate high-performance multiplexed readout of superconducting qubits using a tunable broadband Purcell filter, effectively resolving the fundamental trade-off between measurement speed and photon-noise-induced dephasing. By dynamically tuning the filter parameters, we suppress photon-noise-induced dephasing by a factor of 7 in idle status, while enabling rapid, high-fidelity readout in measurement status. We achieve 99.6\% single-shot readout fidelity with 100~ns readout pulse, limited primarily by relaxation errors during readout. Using a multilevel readout protocol, we further attain 99.9\% fidelity in 50~ns. Simultaneous readout of three qubits using 100~ns pulses achieves an average fidelity of 99.5\% with low crosstalk. Additionally, the readout exhibits high quantum-nondemolition (QND) performance: 99.4\% fidelity over repeated measurements and a low leakage rate below 0.1\%. Building on the tunable broadband filter, we further propose a scalable readout scheme for surface code QEC with enhanced multiplexing capability, offering a promising solution for fast and scalable QEC.
@article{arxiv.2509.11822,
title = {High-performance multiplexed readout of superconducting qubits with a tunable broadband Purcell filter},
author = {Yuzhe Xiong and Zilin Wang and Jiawei Zhang and Xuandong Sun and Zihao Zhang and Peisheng Huang and Yongqi Liang and Ji Jiang and Jiawei Qiu and Yuxuan Zhou and Xiayu Linpeng and Wenhui Huang and Jingjing Niu and Youpeng Zhong and Ji Chu and Song Liu and Dapeng Yu},
journal= {arXiv preprint arXiv:2509.11822},
year = {2025}
}