A couple of articles showed up in the Arxiv today regarding aspects of Quantum Locality (as opposed to quantum non-locality). In essence, both theoretically and experimentally, these attempt to show that QM and Special Relativity are compatible and there is no quantum non-locality. Neither of these papers are close to the last word on the subject.(adsbygoogle = window.adsbygoogle || []).push({});

1. Quantum Locality by Robert Griffiths, well known scientist and author of an oft-referenced textbook on QM. The abstract:

"It is argued that while quantum mechanics contains nonlocal or entangled states, the instantaneous or nonlocal influences sometimes thought to be present due to violations of Bell inequalities in fact arise from mistaken attempts to apply classical concepts and introduce probabilities in a manner inconsistent with the Hilbert space structure of standard quantum mechanics. Instead, Einstein locality is a valid quantum principle: objective properties of individual quantum systems do not change when something is done to another noninteracting system. There is no reason to suspect any conflict between quantum theory and special relativity."

Reference is made to the positions of Bohmians Goldstein and Norsen (who is an advocate of quantum non-locality and is against the relevance of realism in Bell's Theorem).

2. Testing Non-local Realism with Entangled Coherent States by Paternostro and Jeong. Using Leggett as a foundation, they present experiment evidence in contradiction to non-local theories. (If you reject Leggett as relevant, then you will not see this as evidence against non-local realism.)

"We investigate the violation of non-local realism using entangled coherent states (ECS) under nonlinear operations and homodyne measurements. We address recently proposed Leggett-type inequalities, including a class of optimized incompatibility ones and thoroughly assess the effects of detection inefficiency."

This is an expected result, as similar experiments with discrete variables have provided similar results.

As we have had several threads recently about QM vs. SR, I thought this might be of interest.

-DrC

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# Quantum Locality

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