High-fidelity transmon coupler activated CCZ gate on fluxonium qubits

TL;DR

This paper proposes a fast, high-fidelity CCZ gate for fluxonium qubits using a transmon coupler activated by microwave pulses, simplifying calibration and reducing unwanted interactions.

Contribution

It introduces a novel method for implementing a high-fidelity CCZ gate on fluxonium qubits with a transmon coupler, achieving over 99.99% fidelity in simulations.

Findings

Achieves a 95-ns CCZ gate with >99.99% fidelity in noiseless simulations.

Estimates an error rate of about 0.25% considering decoherence effects.

Demonstrates suppression of unwanted ZZ interactions.

Abstract

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.