A quantum computer controlled by superconducting digital electronics at millikelvin temperature - Nature

AbstractThe development of superconducting quantum computing platforms faces considerable scaling challenges because individual signal lines are required to control each qubit. This wiring overhead is a result of the low level of integration between the control electronics at room temperature and the qubits operating at millikelvin temperatures. A promising alternative is to use cryogenic superconducting digital control electronics that coexist with qubits. Here we present an active quantum processor unit in which qubits and single-flux quantum control electronics are integrated into a single multi-chip module via flip-chip bonding. Our system uses digital demultiplexing to distribute control pulses to several qubits, thus breaking the linear scaling of control lines to the number of qubits. With this approach, we demonstrate single-qubit fidelities above 99% and up to 99.9%. Access through your institution Buy or subscribe This is a preview of subscription content, access via your institution Access options Access through your institution Access Nature and 54 other Nature Portfolio journals Get Nature+, our best-value online-access subscription 27,99 € / 30 days cancel any time Learn more Subscribe to this journal Receive 12 digital issues and online access to articles 111,21 € per year only 9,27 € per issue Learn more Buy this articlePurchase on SpringerLinkInstant access to the full article PDF.39,95 €Prices may be subject to local taxes which are calculated during checkout Fig. 1: System level overview.Fig. 2: Single-qubit gate performance.Fig. 3: Single-qubit control with a SFQ DMX.Fig. 4: Single-qubit gate performance through a SFQ DMX. Similar content being viewed by others Multiplexed superconducting qubit control at millikelvin temperatures with a low-power cryo-CMOS multiplexer Article 25 September 2023 A cryogenic on-chip microwave pulse generator for large-scale superconducting quantum computing Article Open access 16 July 2024 CMOS-based cryogenic control of silicon quantum circuits Article 12 May 2021 Data availability The data supporting this study are available on request from the corresponding author. ReferencesArute, F. et al. Quantum supremacy using a programmable superconducting processor. Nature 574, 505–510 (2019).Article Google Scholar Wu, Y. et al. Strong quantum computational advantage using a superconducting quantum processor. Phys. Rev. Lett. 127, 180501 (2021).Article Google Scholar Morvan, A. et al. Phase transitions in random circuit sampling. Nature 634, 328–333 (2024).Article Google Scholar Fowler, A. G., Mariantoni, M., Martinis, J. M. & Cleland, A. N. Surface codes: towards practical large-scale quantum computation. Phys. Rev. A 86, 032324 (2012).Article Google Scholar Krinner, S. et al. Engineering cryogenic setups for 100-qubit scale superconducting circuit systems. EPJ Quantum Technol. https://doi.org/10.1287/ijoc.1090.0342 (2018).Yoo, J. et al. 34.2 A 28-nm bulk-CMOS IC for full control of a superconducting quantum processor unit-cell. In Proc. 2023 IEEE International Solid- State Circuits Conference (ISSCC) 506–508 (IEEE, 2023).Chakraborty, S. et al. A cryo-CMOS low-power semi-autonomous transmon qubit state controller in 14-nm FinFET technology. IEEE J. Solid-State Circuits 57, 3258–3273 (2022).Article Google Scholar McDermott, R. et al. Quantum-classical interface based on single flux quantum digital logic. Quantum Sci. Technol. 3, 024004 (2018).Article Google Scholar Polonsky, S. V. et al. New RSFQ circuits (Josephson junction digital devices). IEEE Trans. Appl. Supercond. 3, 2566–2577 (1993).Article Google Scholar Koch, J. et al. Charge-insensitive qubit design derived from the Cooper pair box. Phys. Rev. A 76, 042319 (2007).Article Google Scholar McDermott, R. & Vavilov, M. G. Accurate qubit control with single flux quantum pulses. Phys. Rev. Appl. 2, 014007 (2014).Article Google Scholar McKay, D. C., Wood, C. J., Sheldon, S., Chow, J. M. & Gambetta, J. M. Efficient Z gates for quantum computing. Phys. Rev. A 96, 022330 (2017).Article Google Scholar Leonard, E. et al. Digital coherent control of a superconducting qubit. Phys. Rev. Appl. 11, 014009 (2019).Article Google Scholar Liu, C. H. et al. Single flux quantum-based digital control of superconducting qubits in a multichip module. PRX Quantum 4, 030310 (2023).Article Google Scholar Somoroff, A. et al. Fluxonium qubits in a flip-chip package. Phys. Rev. Appl. 21, 024015 (2024).Article Google Scholar Castellanos-Beltran, M. A. et al. Coherence-limited digital control of a superconducting qubit using a Josephson pulse generator at 3 K. Appl. Phys. Lett. 122, 192602 (2023).Magesan, E. et al. Efficient measurement of quantum gate error by interleaved randomized benchmarking. Phys. Rev. Lett. 109, 080505 (2012).Article Google Scholar Liebermann, P. J. & Wilhelm, F. K. Optimal qubit control using single-flux quantum pulses. Phys. Rev. Appl. 6, 024022 (2016).Article Google Scholar Li, K., McDermott, R. & Vavilov, M. G. Hardware-efficient qubit control with single-flux-quantum pulse sequences. Phys. Rev. Appl. 12, 014044 (2019).Article Google Scholar Liu, K. et al. Single-flux-quantum-based qubit control with tunable driving strength. Chin. Phys. B 32, 128501 (2023).Article Google Scholar Shillito, R., Hopfmueller, F., Kulchytskyy, B. & Ronagh, P. Compact pulse schedules for high-fidelity single-flux quantum qubit control. Phys. Rev. Applied 24, 014038 (2025).Article Google Scholar Vozhakov, V., Bastrakova, M., Klenov, N., Satanin, A. & Soloviev, I. Speeding up qubit control with bipolar single-flux-quantum pulse sequences. Quantum Sci. Technol. 8, 035024 (2023).Article Google Scholar Catelani, G., Schoelkopf, R. J., Devoret, M. H. & Glazman, L. I. Relaxation and frequency shifts induced by quasiparticles in superconducting qubits. Phys. Rev. B 84, 064517 (2011).Article Google Scholar Liu, K. et al. Quasiparticle dynamics in superconducting quantum-classical hybrid circuits. Phys. Rev. B 108, 064512 (2023).Article Google Scholar Gustavsson, S. et al. Suppressing relaxation in superconducting qubits by quasiparticle pumping. Science 354, 1573–1577 (2016).Article Google Scholar Iaia, V. et al. Phonon downconversion to suppress correlated errors in superconducting qubits. Nat. Commun. 13, 6425 (2022).Article Google Scholar McEwen, M. et al. Resisting high-energy impact events through gap engineering in superconducting qubit arrays. Phys. Rev. Lett. 133, 240601 (2024).Article Google Scholar Liu, C. H. et al. Quasiparticle poisoning of superconducting qubits from resonant absorption of pair-breaking photons. Phys. Rev. Lett. 132, 017001 (2024).Article Google Scholar Kosen, S. et al. Signal crosstalk in a flip-chip quantum processor. PRX Quantum 5, 030350 (2024).Article Google Scholar Levine, H. et al. Demonstrating a long-coherence dual-rail erasure qubit using tunable transmons. Phys. Rev. X 14, 011051 (2024).

Google Scholar Feng, G. et al. Estimating the coherence of noise in quantum control of a solid-state qubit. Phys. Rev. Lett. 117, 260501 (2016).Article Google Scholar Kirichenko, A. F. et al. System and method of flux bias for superconducting quantum circuits. US patent 12,087,503 В2 (2024).Acharya, R. et al. Multiplexed superconducting qubit control at millikelvin temperatures with a low-power cryo-CMOS multiplexer. Nat. Electron. 6, 900–909 (2023).Article Google Scholar Likharev, K. K. & Semenov, V. K. RSFQ logic/memory family: a new Josephson-junction technology for sub-terahertz-clock-frequency digital systems. IEEE Trans. Appl. Supercond. 1, 3–28 (1991).Article Google Scholar Kirichenko, D. E., Sarwana, S. & Kirichenko, A. F. Zero static power dissipation biasing of RSFQ circuits. IEEE Trans. Appl. Supercond. 21, 776–779 (2011).Article Google Scholar Kaplan, S. B. & Mukhanov, O. A. Operation of a superconductive demultiplexer using rapid single flux quantum (RSFQ) technology. IEEE Trans. Appl. Supercond. 5, 2853–2856 (1995).Article Google Scholar Chip Foundry. SEEQC https://seeqc.com/foundry-services (2026).Johansson, J. R., Nation, P. D. & Nori, F. QuTiP 2: a Python framework for the dynamics of open quantum systems. Comput. Phys. Commun. 184, 1234–1240 (2013).Pedersen, L. H., Møller, N. M. & Mølmer, K. Fidelity of quantum operations. Phys. Lett. A 367, 47–51 (2007).Article MathSciNet Google Scholar Wood, C. J. & Gambetta, J. M. Quantification and characterization of leakage errors. Phys. Rev. A 97, 032306 (2018).Article Google Scholar Download referencesAcknowledgementsWe thank the staff of the Seeqc superconducting foundry for the SFQ wafer fabrication and room-temperature characterization.Author informationAuthor notesThese authors contributed equally: Caleb Jordan, Jacob Bernhardt.Authors and AffiliationsSeeqc Inc., Elmsford, NY, USACaleb Jordan, Jacob Bernhardt, Alex Kirichenko, Aaron Somoroff, Kan-Ting Tsai, Jason Walter, Adam Weis, Meng-Ju Yu, Mario Renzullo, Oleg Mukhanov, Daniel Yohannes, Igor Vernik & Shu-Jen HanSeeqc UK, London, UKJoseph Rahamim, Karthik Bharadwaj, Louis Fry-Bouriaux, Katie Porsch, Jerome Javelle & Chris CheckleyAuthorsCaleb JordanView author publicationsSearch author on:PubMed Google ScholarJacob BernhardtView author publicationsSearch author on:PubMed Google ScholarJoseph RahamimView author publicationsSearch author on:PubMed Google ScholarAlex KirichenkoView author publicationsSearch author on:PubMed Google ScholarKarthik BharadwajView author publicationsSearch author on:PubMed Google ScholarLouis Fry-BouriauxView author publicationsSearch author on:PubMed Google ScholarAaron SomoroffView author publicationsSearch author on:PubMed Google ScholarKatie PorschView author publicationsSearch author on:PubMed Google ScholarKan-Ting TsaiView author publicationsSearch author on:PubMed Google ScholarJason WalterView author publicationsSearch author on:PubMed Google ScholarAdam WeisView author publicationsSearch author on:PubMed Google ScholarMeng-Ju YuView author publicationsSearch author on:PubMed Google ScholarMario RenzulloView author publicationsSearch author on:PubMed Google ScholarJerome JavelleView author publicationsSearch author on:PubMed Google ScholarChris CheckleyView author publicationsSearch author on:PubMed Google ScholarOleg MukhanovView author publicationsSearch author on:PubMed Google ScholarDaniel YohannesView author publicationsSearch author on:PubMed Google ScholarIgor VernikView author publicationsSearch author on:PubMed Google ScholarShu-Jen HanView author publicationsSearch author on:PubMed Google ScholarContributionsC.J. and S.-J.H. conceived the project. Experiments were performed by J.B. with assistance from K.B., K.P., J.R., C.J., A.S. and A.W. A.K., C.J. and O.M. designed the devices. C.J. and L.F.-B. performed the simulations. K.-T.T., J.W., M.-J.Y., M.R. and I.V. tested and validated the carrier chip. J.R., K.B., L.F.-B., K.P. and J.J. provided software support. C.C. fabricated the quantum chips. I.V. and D.Y. managed the testing and fabrication resources and facilities. S.-J.H. oversaw the project. C.J. and S.-J.H. wrote the paper with input from all authors.Corresponding authorCorrespondence to Shu-Jen Han.Ethics declarations Competing interests The authors declare no competing interests. Peer review Peer review information Nature Electronics thanks the anonymous reviewers for their contribution to the peer review of this work. Peer reviewer reports are available. Additional informationPublisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.Supplementary informationSupplementary InformationSupplementary discussion, Figs. 1–4 and Table 1.Peer Review FileRights and permissionsSpringer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.Reprints and permissionsAbout this articleCite this articleJordan, C., Bernhardt, J., Rahamim, J. et al. A quantum computer controlled by superconducting digital electronics at millikelvin temperature. Nat Electron (2026). https://doi.org/10.1038/s41928-026-01576-6Download citationReceived: 19 September 2025Accepted: 26 January 2026Published: 10 March 2026Version of record: 10 March 2026DOI: https://doi.org/10.1038/s41928-026-01576-6Share this articleAnyone you share the following link with will be able to read this content:Get shareable linkSorry, a shareable link is not currently available for this article.