Diagonal Bell-basis two-qubit gates with superconducting qubits

Calibrating fast and high-fidelity operations on large-scale quantum processors is a formidable challenge, which has led to the adoption of highly simplified control parametrizations. As qubit coherence continues improving and control errors are becoming important bottlenecks to operations fidelity, it is imperative to refine the design of these controls. In this work, we leverage simultaneous control of the qubit-qubit coupling and microwave pulses to design two-qubit gates that are diagonal in the Bell basis. This family of two-qubit gates promises to be beneficial to both QEC and NISQ applications by targeting very low leakage rates and minimal durations. Using scalable gate calibration techniques, we demonstrate the implementation of SWAP and CZ gates with increased robustness to low-frequency noise.