Any nonclassical effect noticed in measured statistics is usually attributed just to the light state being observed. According to Born’s rule, quantum probabilities are given by the overlap between the system state and measurement states in a quite symmetrical way. We demonstrate that the nonclassicality of the measurement is a necessary condition to obtain nonclassical statistics. To this end, we present a detector characterization for two-observable joint detection processes based on detector tomography. This is particularized to the most common signatures of nonclassical light.

中文翻译：

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伯恩法则中的非经典性和系统设备对称性

在测量统计数据中发现的任何非经典影响通常仅归因于所观察到的光状态。根据伯恩定律，量子概率由系统状态和测量状态之间的重叠以完全对称的方式给出。我们证明了测量的非经典性是获得非经典统计量的必要条件。为此，我们提出了一种基于探测器X射线断层摄影技术的针对两个可观察到的联合探测过程的探测器特征。这是非经典光最常见的特征。