Useful multipartite correlations from useless reduced states
Abstract
Understanding what can be inferred about a multi-particle quantum system from only the knowledge of its subparts is a highly non-trivial task. Clearly, if the global system doesn't contain any information resource, nor do its subparts. However, is the converse also true? We show that the answer to is negative. We provide three two-qubit states that are non-entangled, but such that any three-qubit state compatible with them is entangled. Entanglement can thus be deduced from the mere observation of separable reduced states. We extend this finding to correlations and provide local marginal correlations that are only compatible with global genuinely tripartite non-local correlations.
Cite
@article{arxiv.1203.4968,
title = {Useful multipartite correlations from useless reduced states},
author = {Lars Erik Würflinger and Jean-Daniel Bancal and Antonio Acín and Nicolas Gisin and Tamas Vertesi},
journal= {arXiv preprint arXiv:1203.4968},
year = {2013}
}
Comments
Changed order of presentation, references to previous work of G.Toth, O. G\"uhne, and co-workers added