Coherence-limited digital control of a superconducting qubit using a Josephson pulse generator at 3 K
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Quantum Physics arXiv:2512.07962 (quant-ph) [Submitted on 8 Dec 2025] Title:Coherence-limited digital control of a superconducting qubit using a Josephson pulse generator at 3 K Authors:M. A. Castellanos-Beltran, A. J. Sirois, L. Howe, D. I. Olaya, J. Biesecker, S. P. Benz, P. F. Hopkins View a PDF of the paper titled Coherence-limited digital control of a superconducting qubit using a Josephson pulse generator at 3 K, by M. A. Castellanos-Beltran and 6 other authors View PDF HTML (experimental) Abstract:Compared to traditional semiconductor control electronics (TSCE) located at room temperature, cryogenic single flux quantum (SFQ) electronics can provide qubit measurement and control alternatives that address critical issues related to scalability of cryogenic quantum processors. Single-qubit control and readout have been demonstrated recently using SFQ circuits coupled to superconducting qubits. Experiments where the SFQ electronics are co-located with the qubit have suffered from excess decoherence and loss due to quasiparticle poisoning of the qubit. A previous experiment by our group showed that moving the control electronics to the 3 K stage of the dilution refrigerator avoided this source of decoherence in a high-coherence 3D transmon geometry. In this paper, we also generate the pulses at the 3 K stage but have optimized the qubit design and control lines for scalable 2D transmon devices. We directly compare the qubit lifetime $T_1$, coherence time $T_2^*$ and gate fidelity when the qubit is controlled by the Josephson pulse generator (JPG) circuit versus the TSCE setup. We find agreement to within the daily fluctuations for $T_1$ and $T_2^*$, and agreement to within 10% for randomized benchmarking. We also performed interleaved randomized benchmarking on individual JPG gates demonstrating an average error per gate of $0.46$% showing good agreement with what is expected based on the qubit coherence and higher-state leakage. These results are an order of magnitude improvement in gate fidelity over our previous work and demonstrate that a Josephson microwave source operated at 3 K is a promising component for scalable qubit control. Comments: Subjects: Quantum Physics (quant-ph); Superconductivity (cond-mat.supr-con) Cite as: arXiv:2512.07962 [quant-ph] (or arXiv:2512.07962v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2512.07962 Focus to learn more arXiv-issued DOI via DataCite Journal reference: Appl. Phys. Lett. 122, 192602 (2023) Related DOI: https://doi.org/10.1063/5.0147692 Focus to learn more DOI(s) linking to related resources Submission history From: Manuel Castellanos Beltran [view email] [v1] Mon, 8 Dec 2025 19:00:58 UTC (4,154 KB) Full-text links: Access Paper: View a PDF of the paper titled Coherence-limited digital control of a superconducting qubit using a Josephson pulse generator at 3 K, by M. A. Castellanos-Beltran and 6 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph new | recent | 2025-12 Change to browse by: cond-mat cond-mat.supr-con References & Citations INSPIRE HEP NASA ADSGoogle Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... Data provided by: Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv (What is alphaXiv?) Links to Code Toggle CatalyzeX Code Finder for Papers (What is CatalyzeX?) DagsHub Toggle DagsHub (What is DagsHub?) GotitPub Toggle Gotit.pub (What is GotitPub?) Huggingface Toggle Hugging Face (What is Huggingface?) Links to Code Toggle Papers with Code (What is Papers with Code?) ScienceCast Toggle ScienceCast (What is ScienceCast?) Demos Demos Replicate Toggle Replicate (What is Replicate?) Spaces Toggle Hugging Face Spaces (What is Spaces?) Spaces Toggle TXYZ.AI (What is TXYZ.AI?) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower (What are Influence Flowers?) Core recommender toggle CORE Recommender (What is CORE?) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs. Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)