Experiments to test Bell's theorem in quantum mechanics
"Bell experiment" redirects here. For the KEK particle physics experiment, see Belle experiment.
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A Bell test, also known as Bell inequality test or Bell experiment, is a real-world physics experiment designed to test the theory of quantum mechanics in relation to Albert Einstein's concept of local realism. Named for John Stewart Bell, the experiments test whether or not the real world satisfies local realism, which requires the presence of some additional local variables (called "hidden" because they are not a feature of quantum theory) to explain the behavior of particles like photons and electrons. As of 2015[update], all Bell tests have found that the hypothesis of local hidden variables is inconsistent with the way that physical systems behave.[1]
According to Bell's theorem, if nature actually operates in accord with any theory of local hidden variables, then the results of a Bell test will be constrained in a particular, quantifiable way. If a Bell experiment is performed and the results are not thus constrained, then the hypothesized local hidden variables cannot exist. Such results would support the position that there is no way to explain the phenomena of quantum mechanics in terms of a more fundamental description of nature that is more in line with the rules of classical physics.
Many types of Bell tests have been performed in physics laboratories, often with the goal of ameliorating problems of experimental design or set-up that could in principle affect the validity of the findings of earlier Bell tests. This is known as "closing loopholes in Bell tests".[1]
Bell inequality violations are also used in some quantum cryptography protocols, whereby a spy's presence is detected when Bell's inequalities cease to be violated.
^ abMarkoff, Jack (21 October 2015). "Sorry, Einstein. Quantum Study Suggests 'Spooky Action' Is Real". New York Times. Retrieved 21 October 2015.
A Belltest, also known as Bell inequality test or Bell experiment, is a real-world physics experiment designed to test the theory of quantum mechanics...
as with John Stewart Bell's original inequality, is a constraint—on the statistical occurrence of "coincidences" in a Belltest—which is necessarily true...
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system passes through an interaction site. In John Bell's 1964 paper that inspired the Belltest, it was assumed that the outcomes A and B could each...
the outcome at the second location. However, so-called "loophole-free" Belltests have since been performed where the locations were sufficiently separated...
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entanglement Bell's theorem, published in 1964 Bell state Belltest experiments CHSH inequality, an experiment-practical formulation of Bell's theorem GHZ...
in the test flights. These first flights were just sharp leaps, but proved the concept and persuaded the military to fund development. The Bell company...
validity of the findings of earlier Belltests. This is known as "closing loopholes in Belltests". To date, Belltests have found that the hypothesis of...
causality as local realism. Belltest experiments show that quantum mechanics broadly violates the inequalities established in Bell's theorem. According to...
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Alexander Graham Bell (/ˈɡreɪ.əm/, born Alexander Bell; March 3, 1847 – August 2, 1922) was a Scottish-born Canadian-American inventor, scientist and...
version being developed by Northrop Grumman and Bell Helicopter as a cargo resupply demonstrator. The test aircraft flew on 10 December 2010 at the Yuma...
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According to Bell's theorem, if nature actually operates in accord with any theory of local hidden variables, then the results of a Belltest will be constrained...
coaxial conductor line for first tests of long-distance transmission in various frequencies. On January 1, 1925, Bell Telephone Laboratories, Inc. was...
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first experimental test of the CHSH-Bell's theorem predictions. This was the first experimental observation of a violation of a Bell inequality. In 1974...