Published February 27, 2025 | Published
Journal Article Open

Hardware-efficient quantum error correction via concatenated bosonic qubits

Putterman, Harald1 ORCID icon
Noh, Kyungjoo1 ORCID icon
Hann, Connor T.1 ORCID icon
MacCabe, Gregory S.1 ORCID icon
Aghaeimeibodi, Shahriar1 ORCID icon
Patel, Rishi N.1 ORCID icon
Lee, Menyoung1 ORCID icon
Jones, William M.1 ORCID icon
Moradinejad, Hesam1
Rodriguez, Roberto1
Mahuli, Neha1
Rose, Jefferson1
Owens, John Clai1 ORCID icon
Levine, Harry1 ORCID icon
Rosenfeld, Emma1, 2
Reinhold, Philip1
Moncelsi, Lorenzo1 ORCID icon
Alcid, Joshua Ari1
Alidoust, Nasser1
Arrangoiz-Arriola, Patricio1
Barnett, James1
Bienias, Przemyslaw1
Carson, Hugh A.1
Chen, Cliff1
Chen, Li1
Chinkezian, Harutiun1
Chisholm, Eric M.1
Chou, Ming-Han1 ORCID icon
Clerk, Aashish1, 3 ORCID icon
Clifford, Andrew1
Cosmic, R.1
Curiel, Ana Valdes1
Davis, Erik1
DeLorenzo, Laura1, 2
D'Ewart, J. Mitchell1
Diky, Art1
D'Souza, Nathan1
Dumitrescu, Philipp T.1 ORCID icon
Eisenmann, Shmuel1
Elkhouly, Essam1
Evenbly, Glen1
Fang, Michael T.1
Fang, Yawen1 ORCID icon
Fling, Matthew J.1
Fon, Warren1 ORCID icon
Garcia, Gabriel1
Gorshkov, Alexey V.1 ORCID icon
Grant, Julia A.1
Gray, Mason J.1 ORCID icon
Grimberg, Sebastian1 ORCID icon
Grimsmo, Arne L.1 ORCID icon
Haim, Arbel1
Hand, Justin1
He, Yuan1
Hernandez, Mike1
Hover, David1
Hung, Jimmy S. C.1 ORCID icon
Hunt, Matthew1
Iverson, Joe1
Jarrige, Ignace1 ORCID icon
Jaskula, Jean-Christophe1 ORCID icon
Jiang, Liang1, 3
Kalaee, Mahmoud1
Karabalin, Rassul1
Karalekas, Peter J.1 ORCID icon
Keller, Andrew J.1 ORCID icon
Khalajhedayati, Amirhossein1 ORCID icon
Kubica, Aleksander1, 4 ORCID icon
Lee, Hanho1 ORCID icon
Leroux, Catherine1
Lieu, Simon1
Ly, Victor1
Madrigal, Keven Villegas1
Marcaud, Guillaume1 ORCID icon
McCabe, Gavin1 ORCID icon
Miles, Cody1
Milsted, Ashley1 ORCID icon
Minguzzi, Joaquin1
Mishra, Anurag1
Mukherjee, Biswaroop1
Naghiloo, Mahdi1
Oblepias, Eric1
Ortuno, Gerson1
Pagdilao, Jason1
Pancotti, Nicola1 ORCID icon
Panduro, Ashley1
Paquette, JP1
Park, Minje1
Peairs, Gregory A.1 ORCID icon
Perello, David1 ORCID icon
Peterson, Eric C.1
Ponte, Sophia1
Preskill, John1, 5 ORCID icon
Qiao, Johnson1 ORCID icon
Refael, Gil1, 5 ORCID icon
Resnick, Rachel1, 2
Retzker, Alex1, 6 ORCID icon
Reyna, Omar A.1
Runyan, Marc1
Ryan, Colm A.1 ORCID icon
Sahmoud, Abdulrahman1
Sanchez, Ernesto1
Sanil, Rohan1
Sankar, Krishanu1
Sato, Yuki1
Scaffidi, Thomas1, 7 ORCID icon
Siavoshi, Salome1
Sivarajah, Prasahnt1 ORCID icon
Skogland, Trenton1
Su, Chun-Ju1
Swenson, Loren J.1
Teo, Stephanie M.1
Tomada, Astrid1
Torlai, Giacomo1 ORCID icon
Wollack, E. Alex1 ORCID icon
Ye, Yufeng1 ORCID icon
Zerrudo, Jessica A.1
Zhang, Kailing1
Brandão, Fernando G. S. L.1, 5 ORCID icon
Matheny, Matthew H.1 ORCID icon
Painter, Oskar1, 5 ORCID icon
  • 1. ROR icon Amazon (United States)
  • 2. ROR icon Google (United States)
  • 3. ROR icon University of Chicago
  • 4. ROR icon Yale University
  • 5. ROR icon California Institute of Technology
  • 6. ROR icon Hebrew University of Jerusalem
  • 7. ROR icon University of California, Irvine

Abstract

To solve problems of practical importance, quantum computers probably need to incorporate quantum error correction, in which a logical qubit is redundantly encoded in many noisy physical qubits. The large physical-qubit overhead associated with error correction motivates the search for more hardware-efficient approaches. Here, using a superconducting quantum circuit, we realize a logical qubit memory formed from the concatenation of encoded bosonic cat qubits with an outer repetition code of distance d=5 (ref.10). A stabilizing circuit passively protects cat qubits against bit flips. The repetition code, using ancilla transmons for syndrome measurement, corrects cat qubit phase flips. We study the performance and scaling of the logical qubit memory, finding that the phase-flip correcting repetition code operates below the threshold. The logical bit-flip error is suppressed with increasing cat qubit mean photon number, enabled by our realization of a cat-transmon noise-biased CX gate. The minimum measured logical error per cycle is on average 1.75(2)% for the distance-3 code sections, and 1.65(3)% for the distance-5 code. Despite the increased number of fault locations of the distance-5 code, the high degree of noise bias preserved during error correction enables comparable performance. These results, where the intrinsic error suppression of the bosonic encodings enables us to use a hardware-efficient outer error-correcting code, indicate that concatenated bosonic codes can be a compelling model for reaching fault-tolerant quantum computation.

Copyright and License

© The Author(s) 2025. This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.

Acknowledgement

We thank the staff from across the AWS Center for Quantum Computing that enabled this project. We also thank F. Harrison, H. Atwater, D. Tirrell and T. Rosenbaum at Caltech and S. Severini, B. Vass, J. Hamilton, N. Bshara and P. DeSantis at AWS for their involvement and support of the research activities at the AWS Center for Quantum Computing.

Data Availability

Data for the logical qubit memory experiment can be found at Zenodo (https://doi.org/10.5281/zenodo.14257632; ref. 66).

Supplemental Material

Supplementary Information

This file contains Supplementary Sections A–K, including Supplementary Figs. 1–41 and Supplementary References – see Contents page for details.

Peer Review File

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Additional details

Created:
September 25, 2025
Modified:
September 25, 2025