Testing quantum correlations versus single-particle properties within Leggett's model and beyond

Branciard, Cyril, Brunner, Nicolas, Gisin, Nicolas, Kurtsiefer, Christian, Lamas-Linares, Antia, Ling, Alexander and Scarani, Valerio (2008) Testing quantum correlations versus single-particle properties within Leggett's model and beyond. Nature Physics, 4 9: 681-685. doi:10.1038/nphys1020


Author Branciard, Cyril
Brunner, Nicolas
Gisin, Nicolas
Kurtsiefer, Christian
Lamas-Linares, Antia
Ling, Alexander
Scarani, Valerio
Title Testing quantum correlations versus single-particle properties within Leggett's model and beyond
Journal name Nature Physics   Check publisher's open access policy
ISSN 1745-2473
1745-2481
Publication date 2008-09
Sub-type Article (original research)
DOI 10.1038/nphys1020
Volume 4
Issue 9
Start page 681
End page 685
Total pages 5
Place of publication London, U.K.
Publisher Nature Publishing Group
Language eng
Formatted abstract
Quantum theory predicts and experiments confirm that nature can produce correlations between distant events that are non-local in the sense of violating a Bell inequality. Nevertheless, Bell's strong sentence 'Correlations cry out for explanations' (ref. 2) remains relevant. The maturing of quantum information science and the discovery of the power of non-local correlations, for example for cryptographic key distribution beyond the standard quantum key distribution schemes, strengthen Bell's wish and make it even more timely. In 2003, Leggett proposed an alternative model for non-local correlations that he proved to be incompatible with quantum predictions. We present here a new approach to this model, along with new inequalities for testing it. These inequalities can be derived in a very simple way, assuming only the non-negativity of probability distributions; they are also stronger than previously published and experimentally tested Leggett-type inequalities. The simplest of the new inequalities is experimentally violated. Then we go beyond Leggett's model, and show that we cannot ascribe even partially defined individual properties to the components of a maximally entangled pair.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ
Additional Notes Published under Letters.

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Mathematics and Physics
 
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Created: Thu, 24 Mar 2011, 08:29:18 EST by Mr Cyril Branciard on behalf of Physics