A major source of error in quantum error correction (QEC) arises from imperfect two-qubit gates, where leakage errors are notoriously difficult to correct within the QEC framework. The iswap gate’s inherently low-leakage nature makes it a compelling approach to address this challenge. However, its implementation in transmon qubits is hindered by parasitic $ZZ$ coupling induced by the required $XY$ interaction, posing a significant challenge for achieving high-fidelity control. In this work, we propose a Graph Surgery framework to theoretically analyze this problem and present a dual-microwave-drive scheme that dynamically cancels $ZZ$ interaction. To address residual transition errors, which we identified as the key bottleneck after $ZZ$ suppression, we further develop the Calibrated Derivative Error Nulling via Correlated Envelopes pulse-shaping protocol. Through this optimized approach, we demonstrate a 46-ns iswap gate with a fidelity of $(99.84\pm 0.06)\%$, suppressing intrinsic leakage to $(3.5\pm 2.6)\times {10}^{-5}$ and conditional phase error to $2.1\times {10}^{-6}$. The scheme features low dependency on specific hardware parameters and requires no auxiliary control architecture. Our results provide a flexible pathway to mitigate leakage challenges, establishing the iswap gate as a high-fidelity primitive for scalable QEC architectures.

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• Quantum computation
• Quantum control
• Quantum gates
• Superconducting qubits