Demonstration of the Two-Fluxonium Cross-Resonance Gate

作者：Ebru Doğan, Dario Rosenstock, Loïck Le Guevel, Haonan Xiong, Raymond Mencia, Aaron Somoroff, Konstantin Nesterov, Maxim Vavilov, Vladimir Manucharyan, Chen Wang · 发表于：arXiv (Cornell University) · 年份：2022 · DOI：10.48550/arxiv.2204.11829 · 被引用次数：4 · 研究领域：Atomic and Subatomic Physics Research、Quantum and electron transport phenomena、Physics of Superconductivity and Magnetism

The superconducting fluxonium qubit has a great potential for high-fidelity quantum gates with its long coherence times and strong anharmonicity at the half flux quantum sweet spot. However, current implementations of two-qubit gates compromise fluxonium's coherence properties by requiring either a temporary population of the non-computational states or tuning the magnetic flux off the sweet spot. Here we realize a fast all-microwave cross-resonance gate between two capacitively-coupled fluxoniums with the qubit dynamics well confined to the computational space. We demonstrate a direct CNOT gate in 70 ns with fidelity up to $\mathcal{F}=0.9949(6)$ despite the limitations of a sub-optimal measurement setup and device coherence. Our results project a possible pathway towards reducing the two-qubit error rate below $10^{-4}$ with present-day technologies.