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- Chen, Liangyu, 1994, et al.
(author)
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Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier
- 2023
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In: npj Quantum Information. - : Springer Science and Business Media LLC. - 2056-6387. ; 9:1
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Journal article (peer-reviewed)abstract
- High-fidelity and rapid readout of a qubit state is key to quantum computing and communication, and it is a prerequisite for quantum error correction. We present a readout scheme for superconducting qubits that combines two microwave techniques: applying a shelving technique to the qubit that reduces the contribution of decay error during readout, and a two-tone excitation of the readout resonator to distinguish among qubit populations in higher energy levels. Using a machine-learning algorithm to post-process the two-tone measurement results further improves the qubit-state assignment fidelity. We perform single-shot frequency-multiplexed qubit readout, with a 140 ns readout time, and demonstrate 99.5% assignment fidelity for two-state readout and 96.9% for three-state readout–without using a quantum-limited amplifier.
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