99.9%-fidelity in measuring a superconducting qubit

• URL: http://arxiv.org/abs/2412.13849v2
• Date: Thu, 19 Dec 2024 13:04:28 GMT
• Title: 99.9%-fidelity in measuring a superconducting qubit
• Authors: Can Wang, Feng-Ming Liu, He Chen, Yi-Fei Du, Chong Ying, Jian-Wen Wang, Yong-Heng Huo, Cheng-Zhi Peng, Xiaobo Zhu, Ming-Cheng Chen, Chao-Yang Lu, Jian-Wei Pan,
• Abstract summary: Quantum state measurement lags nearly an order of magnitude behind quantum gate operations in speed and fidelity. Here, we design a novel architecture to implement the long-sought longitudinal interaction scheme between qubits and resonators. Our experimental results demonstrate a measurement fidelity of 99.8% in 202 ns without the need for any first-stage amplification.
• Score: 7.469716894645766
• License:
• Abstract: Despite the significant progress in superconducting quantum computation over the past years, quantum state measurement still lags nearly an order of magnitude behind quantum gate operations in speed and fidelity. The main challenge is that the strong coupling and readout signal used to probe the quantum state may also introduce additional channels which may cause qubit state transitions. Here, we design a novel architecture to implement the long-sought longitudinal interaction scheme between qubits and resonators. This architecture not only provides genuine longitudinal interaction by eliminating residual transversal couplings, but also introduces proper nonlinearity to the resonator that can further minimize decay error and measurement-induced excitation error. Our experimental results demonstrate a measurement fidelity of 99.8% in 202 ns without the need for any first-stage amplification. After subtracting the residual preparation errors, the pure measurement fidelity is above 99.9%. Our scheme is compatible with the multiplexing readout scheme and can be used for quantum error correction.

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