Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier

Liangyu Chen; Hang Xi Li; Yong Lu; Christopher W. Warren; Christian J. Križan; Sandoko Kosen; Marcus Rommel; Shahnawaz Ahmed; Amr Osman; Janka Biznárová; Anita Fadavi Roudsari; Benjamin Lienhard; Marco Caputo; Kestutis Grigoras; Leif Grönberg; Joonas Govenius; Anton Frisk Kockum; Per Delsing; Jonas Bylander; Giovanna Tancredi

doi:10.1038/s41534-023-00689-6

Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier

Liangyu Chen (Corresponding Author), Hang Xi Li, Yong Lu, Christopher W. Warren, Christian J. Križan, Sandoko Kosen, Marcus Rommel, Shahnawaz Ahmed, Amr Osman, Janka Biznárová, Anita Fadavi Roudsari, Benjamin Lienhard, Marco Caputo, Kestutis Grigoras, Leif Grönberg, Joonas Govenius, Anton Frisk Kockum, Per Delsing, Jonas Bylander (Corresponding Author), Giovanna Tancredi (Corresponding Author)

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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.

Original language	English
Article number	26
Number of pages	7
Journal	NPJ Quantum Information
Volume	9
Issue number	1
DOIs	https://doi.org/10.1038/s41534-023-00689-6
Publication status	Published - Mar 2023
MoE publication type	A1 Journal article-refereed

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Chen, L., Li, H. X., Lu, Y., Warren, C. W., Križan, C. J., Kosen, S., Rommel, M., Ahmed, S., Osman, A., Biznárová, J., Fadavi Roudsari, A., Lienhard, B., Caputo, M., Grigoras, K., Grönberg, L., Govenius, J., Kockum, A. F., Delsing, P., Bylander, J., & Tancredi, G. (2023). Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier. NPJ Quantum Information, 9(1), [26]. https://doi.org/10.1038/s41534-023-00689-6

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title = "Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier",

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.",

author = "Liangyu Chen and Li, {Hang Xi} and Yong Lu and Warren, {Christopher W.} and Kri{\v z}an, {Christian J.} and Sandoko Kosen and Marcus Rommel and Shahnawaz Ahmed and Amr Osman and Janka Bizn{\'a}rov{\'a} and {Fadavi Roudsari}, Anita and Benjamin Lienhard and Marco Caputo and Kestutis Grigoras and Leif Gr{\"o}nberg and Joonas Govenius and Kockum, {Anton Frisk} and Per Delsing and Jonas Bylander and Giovanna Tancredi",

note = "Funding Information: We would like to thank Daryoush Shiri for valuable discussions on microwave theory and simulation. The fabrication of our quantum processor was performed in part at Myfab Chalmers and flip-chip integration was done at VTT. We are grateful to the Quantum Device Lab at ETH Z{\"u}rich for sharing their designs of the printed circuit board and sample holder. The device simulations were enabled by resources provided by the Swedish National Infrastructure for Computing (SNIC) at National Supercomputer Centre (NSC) partially funded by the Swedish Research Council through grant agreement no. 2018-05973. This research was financially supported by the Knut and Alice Wallenberg Foundation through the Wallenberg Center for Quantum Technology (WACQT), the Swedish Research Council, and the EU Flagship on Quantum Technology H2020-FETFLAG-2018-03 project 820363 OpenSuperQ. Publisher Copyright: {\textcopyright} 2023, The Author(s).",

year = "2023",

month = mar,

doi = "10.1038/s41534-023-00689-6",

language = "English",

volume = "9",

journal = "NPJ Quantum Information",

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Chen, L, Li, HX, Lu, Y, Warren, CW, Križan, CJ, Kosen, S, Rommel, M, Ahmed, S, Osman, A, Biznárová, J, Fadavi Roudsari, A, Lienhard, B, Caputo, M, Grigoras, K , Grönberg, L , Govenius, J, Kockum, AF, Delsing, P, Bylander, J & Tancredi, G 2023, 'Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier', NPJ Quantum Information, vol. 9, no. 1, 26. https://doi.org/10.1038/s41534-023-00689-6

TY - JOUR

T1 - Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier

AU - Chen, Liangyu

AU - Li, Hang Xi

AU - Lu, Yong

AU - Warren, Christopher W.

AU - Križan, Christian J.

AU - Kosen, Sandoko

AU - Rommel, Marcus

AU - Ahmed, Shahnawaz

AU - Osman, Amr

AU - Biznárová, Janka

AU - Fadavi Roudsari, Anita

AU - Lienhard, Benjamin

AU - Caputo, Marco

AU - Grigoras, Kestutis

AU - Grönberg, Leif

AU - Govenius, Joonas

AU - Kockum, Anton Frisk

AU - Delsing, Per

AU - Bylander, Jonas

AU - Tancredi, Giovanna

N1 - Funding Information: We would like to thank Daryoush Shiri for valuable discussions on microwave theory and simulation. The fabrication of our quantum processor was performed in part at Myfab Chalmers and flip-chip integration was done at VTT. We are grateful to the Quantum Device Lab at ETH Zürich for sharing their designs of the printed circuit board and sample holder. The device simulations were enabled by resources provided by the Swedish National Infrastructure for Computing (SNIC) at National Supercomputer Centre (NSC) partially funded by the Swedish Research Council through grant agreement no. 2018-05973. This research was financially supported by the Knut and Alice Wallenberg Foundation through the Wallenberg Center for Quantum Technology (WACQT), the Swedish Research Council, and the EU Flagship on Quantum Technology H2020-FETFLAG-2018-03 project 820363 OpenSuperQ. Publisher Copyright: © 2023, The Author(s).

PY - 2023/3

Y1 - 2023/3

N2 - 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.

AB - 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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U2 - 10.1038/s41534-023-00689-6

DO - 10.1038/s41534-023-00689-6

M3 - Article

AN - SCOPUS:85150832342

SN - 2056-6387

VL - 9

JO - NPJ Quantum Information

JF - NPJ Quantum Information

IS - 1

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ER -

Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier

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Author Correction: Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier (npj Quantum Information, (2023), 9, 1, (26), 10.1038/s41534-023-00689-6)

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