Abstract
The 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%.
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The data supporting this study are available on request from the corresponding author.
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Acknowledgements
We thank the staff of the Seeqc superconducting foundry for the SFQ wafer fabrication and room-temperature characterization.
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C.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.
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Supplementary discussion, Figs. 1–4 and Table 1.
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Jordan, C., Bernhardt, J., Rahamim, J. et al. A quantum computer controlled by superconducting digital electronics at millikelvin temperature. Nat Electron 9, 287–294 (2026). https://doi.org/10.1038/s41928-026-01576-6
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DOI: https://doi.org/10.1038/s41928-026-01576-6
