1] ICFO-Institut de Ciencies Fotoniques, Castelldefels, Barcelona E-08860, Spain [2] Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada.
Nat Commun. 2013;4:2263. doi: 10.1038/ncomms3263.
In recent years, the use of information principles to understand quantum correlations has been very successful. Unfortunately, all principles considered so far have a bipartite formulation, but intrinsically multipartite principles, yet to be discovered, are necessary for reproducing quantum correlations. Here we introduce local orthogonality, an intrinsically multipartite principle stating that events involving different outcomes of the same local measurement must be exclusive or orthogonal. We prove that it is equivalent to no-signalling in the bipartite scenario but more restrictive for more than two parties. By exploiting this non-equivalence, it is then demonstrated that some bipartite supra-quantum correlations do violate the local orthogonality when distributed among several parties. Finally, we show how its multipartite character allows revealing the non-quantumness of correlations for which any bipartite principle fails. We believe that local orthogonality is a crucial ingredient for understanding no-signalling and quantum correlations.
近年来，利用信息原理来理解量子关联已经取得了很大的成功。不幸的是，迄今为止所有被考虑的原理都具有二分量的形式，但是为了再现量子关联，内在的多分量原理，还有待发现。在这里，我们引入局部正交性，这是一个内在的多分量原理，它表明涉及同一局部测量的不同结果的事件必须是互斥或正交的。我们证明，在二分量情况下，它与无信号原理等效，但对于两个以上的参与者更为严格。通过利用这种非等价性，我们证明了一些二分量超量子关联在分布在多个参与者时确实违反了局部正交性。最后，我们展示了如何利用其多分量特性揭示任何二分量原理都无法揭示的关联的非量子性质。我们相信局部正交性是理解无信号和量子关联的关键因素。
