Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland and Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria.
Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland.
Phys Rev Lett. 2014 Aug 29;113(9):090403. doi: 10.1103/PhysRevLett.113.090403. Epub 2014 Aug 28.
General wisdom tells us that if two quantum states are "macroscopically distinguishable" then their superposition should be hard to observe. We make this intuition precise and general by quantifying the difficulty to observe the quantum nature of a superposition of two states that can be distinguished without microscopic accuracy. First, we quantify the distinguishability of any given pair of quantum states with measurement devices lacking microscopic accuracy, i.e., measurements suffering from limited resolution or limited sensitivity. Next, we quantify the required stability that has to be fulfilled by any measurement setup able to distinguish their superposition from a mere mixture. Finally, by establishing a relationship between the stability requirement and the "distinguishability with inaccurate measurements" of the two superposed states, we demonstrate that, indeed, the more distinguishable the states are, the more demanding the stability requirements.
一般来说，我们都知道如果两个量子态是“宏观可区分的”，那么它们的叠加态就很难被观察到。通过量化在没有微观精度的情况下区分两个可以宏观区分的量子态的叠加的量子性质的难度，我们使这种直觉更加精确和普遍。首先，我们用缺乏微观精度的测量设备（即分辨率或灵敏度有限的测量）来量化任意给定的一对量子态的可区分性。其次，我们量化了任何能够区分它们的叠加态和单纯混合物的测量设备所必需的稳定性。最后，通过建立稳定性要求与两个叠加态的“用不精确测量进行区分”之间的关系，我们证明了，确实，状态越可区分，稳定性要求就越高。
