  The Toffoli gate takes a special place in the quantum information theory. It
opens up a path for efficient implementation of complex quantum algorithms.
Despite tremendous progress of the quantum processors based on the
superconducting qubits, realization of a high-fidelity three-qubit operation is
still a challenging problem. Here, we propose a novel way to perform a
high-fidelity CCZ gate on fluxoniums capacitively connected via a transmon
qubit, activated by a microwave pulse on the coupler. The main advantages of
the approach are relative quickness, simplicity of calibration and significant
suppression of the unwanted longitudinal ZZ interaction. We provide numerical
simulation of 95-ns long gate of higher than 99.99% fidelity with realistic
circuit parameters in the noiseless model and estimate an error of about 0.25%
under the conventional decoherence rates.

Quantum Physics