Determination of the quantum nature of correlations between two spatially separated systems plays a crucial role in quantum information science. Of particular interest is the questions of if and how these correlations enable quantum information protocols to be more powerful. Here, we report on a distributed quantum computation protocol in which the input and output quantum states are considered to be classically correlated in quantum informatics. Nevertheless, we show that the correlations between the outcomes of the measurements on the output state cannot be efficiently simulated using classical algorithms. Crucially, at the same time, local measurement outcomes can be efficiently simulated on classical computers. We show that the only known classicality criterion violated by the input and output states in our protocol is the one used in quantum optics, namely, phase-space nonclassicality. As a result, we argue that the global phase-space nonclassicality inherent within the output state of our protocol represents true quantum correlations.

中文翻译：

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非局部玻色子采样中的量子相关性

确定两个空间分离的系统之间的相关性的量子性质在量子信息科学中起着至关重要的作用。这些相关性是否以及如何使量子信息协议更强大的问题尤其令人关注。在这里，我们报告一种分布式量子计算协议，其中输入和输出量子态被认为是量子信息学中的经典关联。然而，我们表明，使用经典算法无法有效地模拟输出状态下测量结果之间的相关性。至关重要的是，与此同时，可以在经典计算机上有效地模拟本地测量结果。我们表明，在我们的协议中，输入和输出状态所违反的唯一已知的经典性准则是量子光学中使用的一种准则，即相空间非经典性。结果，我们认为协议输出状态中固有的全局相空间非经典性代表了真正的量子相关性。