ICFO-Institut de Ciències Fotòniques, Castelldefels, Barcelona, Spain.
Phys Rev Lett. 2011 Aug 12;107(7):070401. doi: 10.1103/PhysRevLett.107.070401.
The strength of classical correlations is subject to certain constraints, commonly known as Bell inequalities. Violation of these inequalities is the manifestation of nonlocality-displayed, in particular, by quantum mechanics, meaning that quantum mechanics can outperform classical physics at tasks associated with such Bell inequalities. Interestingly, however, there exist situations in which this is not the case. We associate an intriguing class of bound entangled states, constructed from unextendable product bases with a wide family of tasks, for which (i) quantum correlations do not outperform the classical ones but (ii) there exist supraquantum nonsignaling correlations that do provide an advantage.
经典相关性的强度受到某些约束的限制，通常被称为贝尔不等式。违反这些不等式是非局部性的表现，特别是由量子力学表现出来的，这意味着在与这些贝尔不等式相关的任务中，量子力学可以胜过经典物理学。然而，有趣的是，也存在这种情况并非如此的情况。我们将关联到一类有趣的束缚纠缠态，这些态是由具有广泛任务的不可扩展乘积基构造的，对于这些任务，（i）量子相关性并不优于经典相关性，但（ii）存在超量子非信号相关性，这些相关性确实提供了优势。
