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Reid, M. D. (2001)
Languages: English
Types: Preprint

Classified by OpenAIRE into

arxiv: Quantum Physics, Physics::History of Physics
A generalization of the 1935 Einstein-Podolsky-Rosen (EPR) argument for measurements with continuous variable outcomes is presented to establish criteria for the demonstration of the EPR paradox, for situations where the correlation between spatially separated subsystems is not perfect. Two types of criteria for EPR correlations are determined. The first type are based on measurements of the variances of conditional probability distributions and are necessary to reflect directly the situation of the original EPR paradox. The second weaker set of EPR criteria are based on the proven failure of (Bell-type) local realistic theories which could be consistent with a local quantum description for each subsystem. The relationship with criteria sufficient to prove entanglement is established, to show that any demonstration of EPR correlations will also signify entanglement. It is also shown how a demonstration of entanglement between two spatially separated subsystems, if not able to interpreted as a violation of a Bell-type inequality, may be interpreted as a demonstration of the EPR correlations. In particular it is explained how the experimental observation of two-mode squeezing using spatially separated detectors will signify not only entanglement but EPR correlations defined in a general sense.
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    • [26] It is certainly true however that for the case of perfect EPR correlations where all Δix, Δj p = 0, it is required of any local realistic theory that all Δλx = Δλp = 0 to give hidden variables with definite predictions for xˆ and pˆ. This is proved explicitly in the Appendix (as is the case of near-perfect correlation), and gives the situation of the original EPR paradox discussed in Section 3a.
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    • [29] S. L. Braunstein et al, quant-ph/0012001
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