Characterization and Comparison of Energy Relaxation in Fluxonium Qubits
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Quantum Physics arXiv:2603.23636 (quant-ph) [Submitted on 24 Mar 2026] Title:Characterization and Comparison of Energy Relaxation in Fluxonium Qubits Authors:Kate Azar, Lamia Ateshian, Mallika T. Randeria, Renée DePencier Piñero, Jeffrey M. Gertler, Junyoung An, Felipe Contipelli, Leon Ding, Michael Gingras, Kevin Grossklaus, Max Hays, Thomas M. Hazard, Junghyun Kim, Bethany M. Niedzielski, Hannah Stickler, Kunal L. Tiwari, Helin Zhang, Jeffrey A. Grover, Jonilyn L. Yoder, Mollie E. Schwartz, William D. Oliver, Kyle Serniak View a PDF of the paper titled Characterization and Comparison of Energy Relaxation in Fluxonium Qubits, by Kate Azar and 21 other authors View PDF HTML (experimental) Abstract:Fluxonium superconducting qubits have demonstrated long coherence times and high single- and two-qubit gate fidelities, making them a favorable building block for superconducting quantum processors. We investigate the dominant limitations to fluxonium qubit energy relaxation time $T_1$ using a set of eight planar, aluminum-on-silicon qubits. We find that a circuit-based model for capacitive dielectric loss best captures the frequency dependence of $T_1$, which we analyze within both a two-level and a six-level energy relaxation model. We convert the measured $T_1$ into an effective capacitive quality factor $Q_\mathrm{C}^{\mathrm{eff}}$ to compare qubits on equal footing, accounting for independently estimated contributions from $1/f$ flux noise and radiative loss to the control and readout circuitry. We apply this methodology to compare qubits from two fabrication processes: a baseline process and one that applies a fluorine-based wet treatment prior to Josephson junction deposition. We resolve a small improvement of (13.8 $\pm$ 8.4$)\%$ in the process mean $Q_\mathrm{C}^{\mathrm{eff}}$, indicating that the fluorine treatment may have reduced loss from the metal-substrate interface, but did not address the primary source of loss in these fluxonium qubits. Comments: Subjects: Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Cite as: arXiv:2603.23636 [quant-ph] (or arXiv:2603.23636v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2603.23636 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Kate Azar [view email] [v1] Tue, 24 Mar 2026 18:21:42 UTC (14,180 KB) Full-text links: Access Paper: View a PDF of the paper titled Characterization and Comparison of Energy Relaxation in Fluxonium Qubits, by Kate Azar and 21 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph new | recent | 2026-03 Change to browse by: cond-mat cond-mat.mes-hall 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?)