Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, P.O. Box 51, Hungary.
Phys Rev Lett. 2012 Jan 20;108(3):030403. doi: 10.1103/PhysRevLett.108.030403. Epub 2012 Jan 19.
Entanglement and nonlocality are both fundamental aspects of quantum theory, and play a prominent role in quantum information science. The exact relation between entanglement and nonlocality is, however, still poorly understood. Here we make progress in this direction by showing that, contrary to what previous work suggested, quantum nonlocality does not imply entanglement distillability. Specifically, we present analytically a 3-qubit entangled state that is separable along any bipartition. This implies that no bipartite entanglement can be distilled from this state, which is thus fully bound entangled. Then we show that this state nevertheless violates a Bell inequality. Our result also disproves the multipartite version of a long-standing conjecture made by Peres.
纠缠和非局域性都是量子理论的基本方面，在量子信息科学中起着突出的作用。然而，纠缠和非局域性之间的确切关系仍然知之甚少。在这里，我们通过证明与之前的工作所暗示的相反，量子非局域性并不意味着纠缠可提取性，在这方面取得了进展。具体来说，我们分析地给出了一个在任何二分体划分下都是可分离的 3 量子比特纠缠态。这意味着无法从这个态中提取出任何二分体纠缠，因此这个态是完全束缚纠缠的。然后我们证明这个态违反了贝尔不等式。我们的结果也反驳了 Peres 提出的一个长期存在的多体猜想的多体版本。
