Realization of High-Fidelity CZ Gate Based on a Double-Transmon Coupler

Striving for higher gate fidelity is crucial not only for enhancing existing noisy intermediate-scale quantum devices, but also for unleashing the potential of fault-tolerant quantum computation through quantum error correction. A recently proposed theoretical scheme, the double-transmon coupler (DTC), aims to achieve both suppressed residual interaction and a fast high-fidelity two-qubit gate simultaneously, particularly for highly detuned qubits. Harnessing the state-of-the-art fabrication techniques and a modelfree pulse-optimization process based on reinforcemefor example, would\nenable not only efficient faulttolerant quantum computing with error correction but also\neffective mitigation of errors in current noisy intermediate-scale quantum devices. for single-qubit gates. The performance of the DTC scheme demonstrates its potential as a competitive building block for superconducting quantum processors.