DOE OSTI · 1961891
Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier
Abstract
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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Chen, Liangyu (ORCID:0000000250722445), Li, Hang-Xi (ORCID:000000022578306X), Lu, Yong, Warren, Christopher W. (ORCID:0000000161952708), Križan, Christian J. (ORCID:0000000250597998), Kosen, Sandoko (ORCID:0000000195609932), Rommel, Marcus, Ahmed, Shahnawaz, Osman, Amr (ORCID:0000000202901000), Biznárová, Janka, Fadavi Roudsari, Anita (ORCID:0000000211654515), Lienhard, Benjamin (ORCID:0000000152414131), Caputo, Marco, Grigoras, Kestutis, Grönberg, Leif, Govenius, Joonas, Kockum, Anton Frisk, Delsing, Per (ORCID:0000000212223506), Bylander, Jonas (ORCID:000000034521710X), Tancredi, Giovanna (ORCID:0000000236288398). 2023-03-16. Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier. https://doi.org/10.1038/s41534-023-00689-6
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