Absence of Charge Offset Drift in a Transmon Qubit
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arXiv
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| Main Authors: | , , , , , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866917336302223360 |
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| author | Rospars, Adria Hutin, Hector Seis, Yannick Lledó, Cristóbal Assouly, Réouven Cazali, Romain Dassonneville, Rémy Peugeot, Ambroise Blais, Alexandre Bienfait, Audrey Huard, Benjamin |
| author_facet | Rospars, Adria Hutin, Hector Seis, Yannick Lledó, Cristóbal Assouly, Réouven Cazali, Romain Dassonneville, Rémy Peugeot, Ambroise Blais, Alexandre Bienfait, Audrey Huard, Benjamin |
| contents | 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_12367 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Absence of Charge Offset Drift in a Transmon Qubit Rospars, Adria Hutin, Hector Seis, Yannick Lledó, Cristóbal Assouly, Réouven Cazali, Romain Dassonneville, Rémy Peugeot, Ambroise Blais, Alexandre Bienfait, Audrey Huard, Benjamin Quantum Physics Mesoscale and Nanoscale Physics Materials Science 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. |
| title | Absence of Charge Offset Drift in a Transmon Qubit |
| topic | Quantum Physics Mesoscale and Nanoscale Physics Materials Science |
| url | https://arxiv.org/abs/2603.12367 |