Brassard Gilles, Buhrman Harry, Linden Noah, Méthot André Allan, Tapp Alain, Unger Falk
Département IRO, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, Québec H3C 3J7, Canada.
Phys Rev Lett. 2006 Jun 30;96(25):250401. doi: 10.1103/PhysRevLett.96.250401. Epub 2006 Jun 27.
Bell proved that quantum entanglement enables two spacelike separated parties to exhibit classically impossible correlations. Even though these correlations are stronger than anything classically achievable, they cannot be harnessed to make instantaneous (faster than light) communication possible. Yet, Popescu and Rohrlich have shown that even stronger correlations can be defined, under which instantaneous communication remains impossible. This raises the question: Why are the correlations achievable by quantum mechanics not maximal among those that preserve causality? We give a partial answer to this question by showing that slightly stronger correlations would result in a world in which communication complexity becomes trivial.
贝尔证明了量子纠缠使两个类空分离的方能够展现出经典情况下不可能存在的关联。尽管这些关联比经典情况下可实现的任何关联都更强，但它们无法被用来实现瞬时（超光速）通信。然而，波佩斯库和罗尔利希已经表明，甚至可以定义更强的关联，在这种情况下瞬时通信仍然是不可能的。这就提出了一个问题：为什么量子力学可实现的关联在那些保持因果律的关联中不是最大的？我们通过表明稍强一些的关联会导致一个通信复杂性变得微不足道的世界，从而对这个问题给出了部分答案。
