Tunable anharmonicity in Sn-InAs nanowire transmons beyond the short junction limit

• URL: http://arxiv.org/abs/2603.26895v1
• Date: Fri, 27 Mar 2026 18:13:47 GMT
• Title: Tunable anharmonicity in Sn-InAs nanowire transmons beyond the short junction limit
• Abstract summary: In transmons built from hybrid superconductor-semiconductor Josephson elements, the anharmonicity is tunable with gate voltages.<n>Coherent operation of the qubit is still possible at the point of the lowest anharmonicity.
• Score: 0.286745333924505
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: The anharmonicity of a transmon qubit, defined as the difference in energy level spacing, is a key design parameter. In transmons built from hybrid superconductor-semiconductor Josephson elements, the anharmonicity is tunable with gate voltages that control both the Josephson energy and the weak link transparency. In Sn-InAs nanowire transmons, we use two-tone microwave spectroscopy to extract anharmonicity ranging in absolute value from the transmon charging energy $E_c$ to values smaller than $E_c/10$. This behavior contrasts with the predictions of the multi-channel short-junction model, which sets a lower limit on anharmonicity at $E_c/4$. Coherent operation of the qubit is still possible at the point of the lowest anharmonicity. These findings demonstrate the potential of quantum circuits that benefit from widely electrically tunable anharmonicity.

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