Nonlocal Correlations in Quantum Mechanics

I hope to write more on this subject in the future. I posted this on the Knol platform originally. Knol does not exist anymore but this one deserves to be read I thought.

The article by Nicholas Gisin titled “Quantum Nonlocality: How Does Nature Do It?” (Science, Vol. 326 No. 5958, pp. 1357 – 1358) clarifies some of the confusion regarding nonlocal correlations and nonlocal signaling in quantum physics. His main point is:

  • nonlocal correlations of quantum physics are nonsignaling.

The following are quotes from N.Gisin’s “Quantum Nonlocality: How Does Nature Do It?” article. They clarified some of the confusions in my mind. It is important that these comments find a wider readership.

“The pioneering experiment by Clauser and Aspect probing the Bell test [1] suffered from a few loopholes, but these have since been separately closed [2],[3]. Still, correlations cry out for explanations, as emphasized by Bell.”

“All of today’s experimental evidence points to the conclusion that nature is nonlocal. This has implications both for our worldview and for future technologies”

“In modern quantum physics, entanglement is fundamental; furthermore, space is irrelevant—at least in quantum information science, space plays no central role and time is a mere discrete clock parameter. In relativity, space-time is fundamental and there is no place for nonlocal correlations. To put the tension in other words: No story in space-time can tell us how nonlocal correlations happen; hence, nonlocal quantum correlations seem to emerge, somehow, from outside space-time.”

“Some conclude that it must be realism that is faulty. But I don’t see in which sense this could save locality? Moreover, realism is often confused with determinism, an uninteresting terminology issue.”

“Furthermore, in a nonsignaling world, correlations can be nonlocal only if the measurement results were not predetermined. Indeed, if the results were predetermined (and accessible with future theories and technologies), then one could exploit nonlocal correlations to signal. This fact has recently been used to produce bit strings with proven randomness.”

Regarding the uneasiness with nonlocality you should read Gisin’s recent paper [5].

References

[1] S. J. Freedman, J. F. Clauser, Phys. Rev. Lett. 28, 938 (1972).
[2] A. Aspect et al., Phys. Rev. Lett. 49, 91 (1982).
[3] D. N. Matsukevich et al., Phys. Rev. Lett. 100, 150404 (2008).
[4] S. Pironio et al., http://arxiv.org/abs/0911.3427 (2009).
[5] N. Gisin, http://arxiv.org/abs/0901.4255v2 (2009).

Advertisements

About Suresh Emre

I have worked as a physicist at the Fermi National Accelerator Laboratory and the Superconducting Super Collider Laboratory. I am a volunteer for the Renaissance Universal movement. My main goal is to inspire the reader to engage in Self-discovery and expansion of consciousness.
This entry was posted in physics, science and tagged , . Bookmark the permalink.