It is not possible to obtain information about the observable properties of a quantum system without a physical interaction between the system and an external meter. This physical interaction is described by a unitary transformation of the joint quantum state of the system and the meter, which means that the information transfer from the system to the meter depends on the initial quantum coherence of the meter. In the present paper, we analyze the measurement interaction in terms of the changes of the meter state caused by the interaction with the system. The sensitivity of the meter can then be defined by evaluating the distinguishability of meter states for different values of the target observable. It is shown that the sensitivity of the meter requires quantum coherences in the generator observable that determines the magnitude of the backaction of the meter on the system. The tradeoff between measurement resolution and backaction is decided by the relation between sensitivity and quantum coherent uncertainty in the external meter. No matter how macroscopic the device used as a meter is, it must necessarily be quantum coherent in the degrees of freedom that interact with the system being measured.

中文翻译：

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量子系统与外部仪表之间信息交换的不确定性限制

如果没有系统和外部仪表之间的物理交互，就不可能获得有关量子系统可观察特性的信息。这种物理相互作用是通过系统和仪表的联合量子态的酉变换来描述的，这意味着从系统到仪表的信息传输取决于仪表的初始量子相干性。在本文中，我们从与系统交互引起的仪表状态变化方面来分析测量交互。然后可以通过针对不同的目标可观察值评估仪表状态的可区分性来定义仪表的灵敏度。结果表明，仪表的灵敏度需要发生器可观察量中的量子相干性，这决定了仪表在系统上的反作用的幅度。测量分辨率和反作用之间的权衡取决于外部仪表中灵敏度和量子相干不确定性之间的关系。无论用作仪表的设备有多么宏观，它都必须在与被测系统相互作用的自由度上是量子相干的。