High-fidelity transmon-coupler-activated CCZ gate on fluxonium qubits

Physical Review Applied. 2024. Vol. 21. No. 4. P. 0.

Ilya S., Grigoriy M., Moskalenko I., Seidov S., Besedin I.

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 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 a 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.

Keywords: qubits, quantum gates