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This Defense Intelligence Reference Document (DIA-08-1003-016), dated 30 March 2010 and produced by the Defense Intelligence Agency under its Advanced Aerospace Weapon System Applications (AAWSA) Program, reviews quantum entanglement and nonlocality. It asks whether they could carry observer-to-observer signals faster than light or backward in time, with real-time control of a Mars rover as an example. It finds no compelling answer yet and says the question must be settled by experiment.
UNCLASSIFIED/ }P81il 8Pfl8Iilrt Wili &•lb¥ Appendix: Glossary Basis: In quantum mechanics, a choice of an observable quantity that may be complementary to another variable, so that both cannot be measured at the same time. An example is the choice of measuring position, which prevents the simultaneous measurement of momentum. In EPR experiments, one must choose a polarization basis (for example, linear polarization that may be either vertical or horizontal). Since both circular polarization and 45° left/right polarization are linear superpositions of vertical/horizontal polarization, they may not be measured simultaneously. In quantum mechanics, the measurement causes the wave function to collapse to a particular basis value, excluding other possible values. Bell's Theorem: A mathematical proof by John S. Bell (Reference 8) demonstrating that in a polarization-based EPR experiment, the falloff of correlations as the basis angle of a polarization measurement is changed is qualitatively different, as predicted by local hidden-variable theories and by standard quantum mechanics. In particular, local hidden-variable theories predict a linear falloff, while quantum mechanics predicts a quadratic falloff. This difference in predictions is represented as an inequality in measurement intensity ratios that all local hidden variable theories must satisfy, while quantum mechanics does not. Tests of these predictions have been found to agree with quantum mechanics and to falsify local hidden-variable theories. Bilking Paradox: A type of back-in-time communication paradox in which an inconsistent causal loop is created. A well-known example is the Grandmother Paradox, a time-travel scenario from science fiction in which a time traveler travels to the past and kills his grandmother before she had children. The question then arises, How could he have been born if his grandmother had no children? Several works in the physics literature (Reference 17, 18) have concluded that such trans-temporal bilking is impossible, that nature will not permit inconsistent timelike loops, and that it is more likely that some apparatus will fail than that a "bilk" of nature could be achieved. Causality: The observation, which is regarded as a law of physics, that a cause must precede its effects as viewed in any and all reference frames. Sometimes referred to as "Cause and Effect" or "the Law of Cause and Effect." Correlations: The mathematical connection between two variables or two measured quantities. As an example, in an EPR measurement, the basis polarization of one photon is selected, the basis polarization of the twin entangled photon is varied, and the coincidence counting rate versus varied angle is measured to establish the correlation between the two polarizations. Coherence: Describes whether two waves (for example, those arriving at a pair of slits or at a detector) have a definite phase relation (in which case they are completely coherent), have a random phase relation (in which case they are completely incoherent), or have something in between. Coherence-Entanglement Complementarity: The theoretical expectation and experimental observation (Reference 15) that perfect coherence and perfect entanglement cannot be achieved for an entangled pair of photons at the same time. 24 UNCLASSIFIED//f&R 8ffl@Itllt ""I! one I
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 32 pages are in the text index: search them above, or from the library's search.