Is it possible that a measurement of a spin component of a spin-1/2 particle yields the value 100? In 1988 Aharonov, Albert and Vaidman argued that upon pre- and postselection of particular spin states, weakening the coupling of a standard measurement procedure ensures this paradoxical result¹. This theoretical prediction, called weak value, was realised in numerous experiments^{2,3,4,5,6,7,8,9}, but its meaning remains very controversial^{10,11,12,13,14,15,16,17,18,19}, since its “anomalous” nature, i.e., the possibility to exceed the eigenvalue spectrum, as well as its “quantumness” are debated^20,21,22. We address these questions by presenting the first experiment measuring anomalous weak values with just a single click, without the need for statistical averaging. The measurement uncertainty is significantly smaller than the gap between the measured weak value and the nearest eigenvalue. Beyond clarifying the meaning of weak values, demonstrating their non-statistical, single-particle nature, this result represents a breakthrough in understanding the foundations of quantum measurement, showing unprecedented measurement capability for further applications of weak values to quantum photonics.

自旋1/2粒子的自旋成分的测量值是否可能为100？1988年，Aharonov，Albert和Vaidman提出，在对特定自旋态进行预选择和后选择时，减弱标准测量程序的耦合可确保这一矛盾的结果¹。这种理论上的预测称为弱值，已在众多实验^{2、3、4、5、6、7、8、9中}实现，但其含义仍然引起很大争议^{10,11,12,13,14,15,16,17 ，18,19}，因为它的“异常”性质，即超过特征值谱的可能性，以及它的“量子性”，都在争论^20,21,22。我们提出了第一个只需单击一次即可测量异常弱值的实验，而无需进行统计平均，从而解决了这些问题。测量不确定度明显小于测量的弱值和最近的特征值之间的差距。除了阐明弱值的含义，证明其非统计的单粒子性质外，该结果还代表了对量子测量基础的突破，显示了将弱值进一步应用到量子光子学中的空前的测量能力。