High-fidelity iSWAP gate with Double Transmon Coupler

• URL: http://arxiv.org/abs/2604.27080v1
• Date: Wed, 29 Apr 2026 18:19:05 GMT
• Title: High-fidelity iSWAP gate with Double Transmon Coupler
• Abstract summary: Parametric gates offer a versatile solution to strongly couple off-resonant superconducting qubits with suppressed parasitic crosstalk.<n>We demonstrate a parametric iSWAP gate between two transmon qubits using the recently developed double transmon coupler.<n>We achieve a 99.827% gate fidelity in 40ns without any numerical optimization.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Entangling operations are at the heart of all approaches to quantum information processing. Parametric gates, in particular, offer a versatile solution to strongly couple off-resonant superconducting qubits with suppressed parasitic crosstalk to spectator qubits due to frequency-selective activation. In this work, we demonstrate a parametric iSWAP gate between two transmon qubits using the recently developed double transmon coupler (DTC). The DTC supports robust internally-defined cancellation point (``off'' state) for static interactions, while simultaneously mediating a fast parametric coupling between data qubits that can be deployed for high-fidelity two-qubit operations. We use robust phase estimation to calibrate non-commuting error terms in the parametric iSWAP gate, and achieve a 99.827% gate fidelity in 40ns without any numerical optimization. The circuit architecture and calibration techniques developed here are extensible to other gate implementations and qubit modalities, paving the way towards resource-efficient quantum information processing.

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