High-fidelity two-qubit gates are essential for scalable quantum computing. We present a scheme based on superconducting transmon qubits and a control pulse delivery protocol that enables arbitrary controlled-phase gates modulated solely by an independent arbitrary waveform generator pulse. We combined a tunable coupler design with bipolar flux-pulsing to demonstrate a controlled-phase gate, achieving a peak fidelity of 99.5%. Our gates inherit the advantages of both approaches: minimal residual $ZZ$ coupling, built-in echo-like low-frequency noise protection, and time-scale control pulse reproducibility, while remaining easy to calibrate. We optimize the system’s energy levels to mitigate leakage to the coupler and suppress residual interactions. Numerical simulations of the scheme as three qutrits indicate that an error below $1\times {10}^{-3}$ is achievable. We confirm the scalability potential of the proposed scheme on high-fidelity four-qubit and eight-qubit quantum processors.

Close

PrevNext

View figure in article

• Optoelectronics
• Quantum circuits
• Quantum control
• Quantum gates
• Quantum information with solid state qubits
• Superconducting qubits
• Microwave techniques