AI 中文总结
本文实验实现了基于 fluxonium 量子比特与微波驱动 transmon 耦合器的原生 CCZ 门，保真度达 99.39(5)%，性能受相干时间限制，为可扩展超导量子处理器提供了硬件高效的多量子比特门方案。
AI 中文摘要
原生多量子比特门可减少分解为单、两量子比特操作带来的开销，但在可扩展架构中能否同时实现高保真度、简单控制及对寄生相互作用的鲁棒性仍不明确。本文实验实现了一种 65 纳秒的原生受控-受控相位操作，其局部等价于 Toffoli 门，在基于 fluxonium 量子比特通过微波驱动的 transmon 耦合器耦合的三量子比特处理器单元中，该操作的保真度达 99.39(5)%。若采用常规分解方式实现该操作，则需要 CZ 门的保真度约为 99.94%。该门通过单个控制脉冲实现，依赖简单校准程序，性能受限于相干时间。该处理器单元可自然扩展为二维可扩展布局，寄生相互作用低。综上，这些结果表明原生多量子比特门是可扩展超导量子处理器中可行的硬件高效基本单元。
英文摘要
Native multi-qubit gates could reduce the overhead associated with decompositions into single- and two-qubit operations, but whether they can simultaneously provide high fidelity, simple control and robustness against parasitic interactions in scalable architectures remains unclear. Here we experimentally realize a 65-ns native controlled-controlled-phase operation, locally equivalent to the Toffoli gate, with a fidelity of 99.39(5)% in a three-qubit processor unit based on fluxonium qubits coupled via a microwave-driven transmon coupler. The implemented operation would require CZ fidelities of approximately 99.94% if realized through a conventional decomposition. The gate is implemented with a single control pulse, that relies on a simple calibration procedure yielding coherence-limited performance. This processor unit naturally extends to scalable two-dimensional layouts with low parasitic interactions. Altogether, these results establish native multi-qubit gates as a viable hardware-efficient primitive for scalable superconducting quantum processors.
Comments12 pages, 7 figures, 3 tables
