ArXiv · 2026
Tunable couplers have enabled two-qubit gate fidelities in superconducting quantum processors to approach 99.9%, yet simultaneously suppressing residual interactions and maintaining flexible qubit-frequency allocation remain central challenges for scaling. Here, we propose a double-resonator coupler (DRC) consisting of two resonators interconnected by a single Josephson junction and a capacitor. The hybridized resonator modes provide two mediated exchange paths whose interference controls the qubit-qubit interaction. The DRC enables complete cancellation of residual ZZ interaction for qubit-qubit detunings well outside the straddling regime, even in the absence of direct qubit-qubit coupling, thereby relaxing constraints on frequency allocation and qubit placement. Away from the idle point, the same circuit provides a strong ZZ interaction of approximately 70 MHz, enabling a 20 ns controlled-Z gate with simulated coherent infidelity below 10⁻⁵. These results establish the DRC as a flexible single-junction coupler architecture for high-fidelity superconducting quantum processors.
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