Absence of Charge Offset Drift in a Transmon Qubit

Quantum Physics [Submitted on 12 Mar 2026] Absence of Charge Offset Drift in a Transmon Qubit Adria Rospars, Hector Hutin, Yannick Seis, Cristóbal Lledó, Réouven Assouly, Romain Cazali, Rémy Dassonneville, Ambroise Peugeot, Alexandre Blais, Audrey Bienfait, Benjamin Huard Superconducting quantum circuits are sensitive to their electrostatic environment: uncontrolled charges accumulating on the electrodes of a Josephson junction shift the energy levels of a qubit, perturbing its operation and restricting their design. This effect is captured by a single parameter - the charge offset - whose slow, unpredictable drift has proven difficult to eliminate in practice. Here, we report a tantalum-based transmon qubit in which the charge offset remains pinned at zero over nearly three months of measurements, including two thermal cycles, with no observable compromise to the qubit lifetime. This exceptional stability disappears in later cooldowns, indicating a fragile mechanism at play. We attribute it to the inductance of a thin superconducting layer inadvertently formed in parallel with the Josephson junction during fabrication. X-ray surface spectroscopy suggests this layer arises from an incomplete wet-etch of tantalum on sapphire. Deliberately engineering such a layer offers a route to eliminating charge-offset drift in superconducting circuits more broadly. Comments: 21 pages Subjects: Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci) Cite as: arXiv:2603.12367 [quant-ph]   (or arXiv:2603.12367v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2603.12367 Focus to learn more Submission history From: Benjamin Huard [view email] [v1] Thu, 12 Mar 2026 18:36:53 UTC (5,240 KB) Access Paper: HTML (experimental) view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-03 Change to browse by: cond-mat cond-mat.mes-hall cond-mat.mtrl-sci References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation 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 Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)