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AAWSAP DIRD, The Space Communication Implications of Quantum Entanglement and Nonlocality, March 2010

U.S. Department of War · 2010-03-30 · 32 pages · text from the file's own layer

This Defense Intelligence Reference Document, dated 30 March 2010, was prepared by the Defense Intelligence Agency's Defense Warning Office under its Advanced Aerospace Weapon System Applications Program. It reviews quantum entanglement, nonlocality and EPR experiments, and asks whether nonlocal quantum effects could carry observer-to-observer signals faster than light. The paper describes proposed experiments and an example of real-time Earth control of a Mars rover. It concludes that there is no compelling answer yet and that experimental tests are needed.

From the source:Release of 2026-09-18 Incident: 3/30/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD reviews quantum entanglement and nonlocality with a focus on whether those phenomena might be usable as a means of faster-than-light communication between observers, especially for real-time space operations over interplanetary distances. The report surveys the relevant quantum experiments and no-signal theorems, then examines proposed communication schemes based mainly on momentum-entangled photons, including scenarios involving superluminal and retro-causal signaling. However, it repeatedly acknowledges that the central question remains unresolved experimentally, and it gives substantial attention to the coherence-versus-entanglement tradeoff and other features of standard quantum mechanics that may prevent usable signaling even if non-local correlations are experimentally validated. Overall, the document is an exploratory analysis of whether quantum nonlocality could conceivably support a practical communications application rather than a demonstration of prospective utility.

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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 fal loff 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 fa il 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, t hose 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 someth ing 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.
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