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Fast multiplexed superconducting qubit readout with intrinsic Purcell filtering

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arxiv 2409.04967 v2 pith:E2ZHJL3Y submitted 2024-09-08 quant-ph

classification quant-ph
keywords qubitreadoutfastfidelitypurcellresonatorsuperconductingassignment
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Fast and accurate qubit measurement remains a critical challenge on the path to fault-tolerant quantum computing. In superconducting quantum circuits, fast qubit measurement has been achieved using a dispersively coupled resonator with a large external linewidth. This necessitates the use of a Purcell filter that protects the qubit from relaxation through the readout channel. Here we show that a readout resonator and filter resonator, coupled to each other both capacitively and inductively, can produce a compact notch-filter circuit that effectively eliminates the Purcell decay channel through destructive interference. By utilizing linewidths as large as 42 MHz, we perform 56-ns simultaneous readout of four qubits and benchmark an average assignment fidelity of 99.77%, with the highest qubit assignment fidelity exceeding 99.9%. These results demonstrate a significant advancement in speed and fidelity for multiplexed superconducting qubit readout.

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Cited by 4 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Full characterization of measurement-induced transitions of a superconducting qubit

    quant-ph 2025-06 conditional novelty 8.0 of 10

    Readout-induced leakage in high-frequency transmon readout is dominated by inelastic single-photon Raman scattering, with rate proportional to drive power and to the dissipative impedance at the emitted-photon frequency.

  2. Suppression of measurement-induced state transitions in cos{\phi}-coupling transmon readout

    quant-ph 2025-09 conditional novelty 6.0 of 10

    A cos-phi-coupled transmon readout is experimentally free of measurement-induced state transitions up to roughly 300 photons, with flux-controlled activation of specific transitions.

  3. Intrinsic Multi-Mode Interference for Passive Suppression of Purcell Decay in Superconducting Circuits

    quant-ph 2025-07 conditional novelty 6.0 of 10

    Breaking the symmetry of a transmon capacitor activates multi-mode interference that can suppress Purcell decay, shown analytically, in simulation, and in one four-qubit device.

  4. High-power readout of a transmon qubit using a nonlinear coupling

    quant-ph 2025-07 conditional novelty 6.0 of 10

    A transmon molecule with nonlinear cosφ coupling achieves 99.21% readout fidelity at 89 photons and remains QND with less than 4% errors up to 300 photons, with a theoretical critical photon number of 377.

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