@article{3262694e69214e9c87fecca153cd73c5,
title = "Nonlocal hidden-variable theories and quantum mechanics: An incompatibility theorem",
abstract = "It is argued that among possible nonlocal hidden-variable theories a particular class (called here {"}crypto-nonlocal{"} or CN) is relatively plausible on physical grounds. CN theories have the property that (for example) the two photons emitted in an atomic cascade process are indistinguishable in their individual statistical properties from photons emitted singly, and that in the latter case the effects of nonlocality are unobservable. It is demonstrated that all CN theories are constrained by inequalities which are violated by the quantum-mechanical predictions; these inequalities bear no simple relation to Bell's inequalities, and an explicit example is constructed of a CN theory which violates the latter. It is also shown that while existing experiments cannot rule out general CN theories, they do rule out (subject to a few caveats such as the usual ones concerning the well-known {"}loopholes{"}) the subclass in which the photon polarizations are linear.",
keywords = "Hidden-variable theories, Nonlocality, Quantum mechanics",
author = "Leggett, {A. J.}",
note = "Funding Information: The kernel of this work was done during a semester spent at the University of Science and Technology, Kumasi, Ghana (UST), on secondment from the University of Sussex in the fall of 1976, and the present manuscript was written, with the exception of the present Sec. 4 and some minor updates and revisions, at Sussex over the next two years. I would like to thank my colleagues at the UST for their hospitality in Kumasi, and the U.K. Inter-Universities Council for Higher Education Overseas for financial support for my visit there. I am grateful to Dr. L. Allen, Dr. G. Barton, Dr. R. Kuhn, and, most particularly, the late Prof. J. S. Bell for their helpful comments at that time; and to Dipankar Home and Abner Shimony for theirs a quarter of a century later, which not only led to an improvement of the manuscript but persuaded me that it might still be worth publishing. I am particularly grateful to Abner Shimony for his comments on the near-final version. The original Sec. 4 turned out to have contained a major error, and the necessary (and nontrivial) rewriting of this section, as well as the final revision of the manuscript, was carried out during a very pleasant stay at the University of Florida, Gainesville and supported by the National Science Foundation under Grant NSF-EIA01-21568.",
year = "2003",
month = oct,
doi = "10.1023/A:1026096313729",
language = "English (US)",
volume = "33",
pages = "1469--1493",
journal = "Foundations of Physics",
issn = "0015-9018",
publisher = "Springer Netherlands",
number = "10",
}