光晶格钟平台中的qutrit纠缠与联合多参数估计
Qutrit entanglement and joint multi-parameter estimation in an optical clock platform
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中文总结 AI 辅助
本研究在光晶格钟平台中实验实现真实两qutrit纠缠，构建最优计量探针态与抗噪读出电路，联合估计双钟跃迁注入相位，其方差低于理想两能级单独传感阈值，为高维量子信息科学提供关键基础。
中文摘要 AI 辅助
量子计量学利用纠缠将测量精度提升至经典极限之上。标准协议依赖两能级量子比特估计单一参数，而将其扩展至纠缠的多能级qudit可在单个探针内实现多个参数的最优同时估计。然而，在原子钟中生成此类多能级纠缠并将其用于联合多参数估计仍是一项悬而未决的挑战。本文在光晶格钟平台中实验演示了真实qutrit纠缠与联合多参数估计。通过对束缚于三重光镊中的$^{88}\ ext{Sr}$原子的基态及两个精细结构钟态进行操控，我们生成了最大纠缠的两qutrit态，其损耗后选择保真度为F=0.85(1)，验证了真实多能级纠缠的存在。利用该高维纠缠，我们在理论上构建并实验实现了最优两qutrit计量探针态与抗噪读出电路，以同时估计两个光晶格钟跃迁上的注入相位。我们观测到联合估计方差低于理想两能级单独传感阈值，并从理论上证明，在电路级噪声下，该优势在当前最先进的原子数条件下依然存在。这些结果为利用中性原子内部能级编码高维态开展量子信息科学提供了关键构建模块。
英文摘要
Quantum metrology harnesses entanglement to improve measurement precision beyond classical limits. While standard protocols rely on two-level qubits to estimate a single parameter, extending them to entangled multi-level qudits enables the optimal simultaneous estimation of multiple parameters within a single probe. However, generating such multi-level entanglement and harnessing it for joint multi-parameter estimation in atomic clocks has remained an outstanding challenge. Here, we experimentally demonstrate genuine qutrit entanglement and joint multi-parameter estimation in an optical clock platform. Leveraging control over the ground state and two fine-structure clock states of $^{88}\text{Sr}$ atoms trapped in triple-magic optical tweezers, we generate a maximally entangled two-qutrit state with a loss-postselected fidelity of F = 0.85(1), certifying genuine multi-level entanglement. Taking advantage of this high-dimensional entanglement, we theoretically construct and experimentally realize an optimal two-qutrit metrological probe state and noise-robust readout circuit to simultaneously estimate injected phases on two optical clock transitions. We observe a joint estimation variance below the ideal individual two-level sensing threshold, and show theoretically that this advantage persists at state-of-the-art atom numbers under circuit-level noise. These results demonstrate the key building blocks towards quantum information science with high-dimensional states encoded in the internal energy levels of neutral atoms.
