AI 中文总结
研究利用线性光学平台，通过非厄米可观测量实现量子参数估计，将参数编码在单光子态并用萨格纳克干涉仪读出，观察到相比厄米可观测量误差传播方差减小，为非厄米可观测量读出提供实验途径并阐明其意义。
AI 中文摘要
传统上，量子参数估计的精度受基于厄米测量框架的量子克拉美罗界限制。近期对非厄米系统的研究为提高参数估计灵敏度带来新可能。在此，我们在一个线性光学平台上通过使用非厄米可观测量来实验实现量子参数估计。该参数编码在单光子探测态中，并用萨格纳克干涉仪读出，这使我们能从干涉条纹重建所实现非厄米可观测量的复期望值。与相同探测态模型的最优厄米可观测量相比，我们观察到误差传播方差减小。在振幅阻尼噪声下此优势依然明显。我们进一步将完整光学测量分析为物理正算符值测量（POVM），并通过相应的经典费舍尔信息（CFI）表明，当包含所有输出端口时，观察到的非厄米优势与标准量子计量极限一致。我们的结果为非厄米可观测量读出提供了一条实验途径，并阐明了其在量子传感中的操作意义。
英文摘要
The precision of quantum parameter estimation is traditionally constrained by the quantum Cramér-Rao bound, which is based on the Hermitian measurement framework. Recent studies of non-Hermitian systems have suggested new possibilities for enhancing parameter-estimation sensitivity. Here, we experimentally realize quantum parameter estimation using a non-Hermitian observable on a linear optical platform. The parameter is encoded in single-photon probe states and read out with a Sagnac interferometer, which allows us to reconstruct the complex expectation value of the implemented non-Hermitian observable from interference fringes. We observe a reduced error-propagation variance compared with the optimal Hermitian observable for the same probe-state model. This advantage remains visible under amplitude-damping noise. We further analyze the complete optical measurement as a physical positive-operator-valued measure (POVM) and show, through the corresponding classical Fisher information (CFI), that the observed non-Hermitian advantage is consistent with the standard quantum metrological limit when all output ports are included. Our results provide an experimental route to non-Hermitian observable readout and clarify its operational meaning in quantum sensing.
Comments7 pages, 3 figures
