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arXiv · 2409.04967

Fast multiplexed superconducting qubit readout with intrinsic Purcell filtering

Peter A. Spring·Luka Milanovic·Yoshiki Sunada·Shiyu Wang·Arjan F. van Loo·Shuhei Tamate·Yasunobu Nakamura
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Abstract

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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Peter A. Spring, Luka Milanovic, Yoshiki Sunada, Shiyu Wang, Arjan F. van Loo, Shuhei Tamate, Yasunobu Nakamura. 2024-09-08. Fast multiplexed superconducting qubit readout with intrinsic Purcell filtering. https://doi.org/10.1103/prxquantum.6.020345

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