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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.
UNCLASSIFIED/ /FOR OFFI&iIAk W&li OPlklf I. Quantum Entanglement, Nonlocality, and EPR Experiments In the quantum mechanical description of elementary entities like photons, there is a duality between the description as a particle and as a wave. Photons can be thought of as traveling through space as waves but delivering energy (and other conserved quantities) at detection as particles. By choosing the kinds of measurements made on such objects, one can force wave-like or particle-like behavior to be exhibited in the measurements results. Between the entangled parts of a quantum system (for example, the emission of a pair of entangled photons), this wave-like or particle-like behavior in a measurement on one part of the system may force similar behavior in the other part. This is considered further in Section IV below. The quantum entanglement condition is usually a consequence of some conservation law acting within the system, so that the subsystems are connected by the conserved quantities. For example, if two photons are emitted back to back in a joint state that has zero angular momentum and positive parity, then whatever linear or circular polarization state one photon is measured to have, the other photon must have an identical polarization if measured in the same basis (linear or circular). This condition must exist to ensure that the net angular momentum of the two photon states is zero. In this situation, if the photons are measured for circular polarization, they must both be in states of right circular polarization or in states of left circular polarization. Because linear polarization is a coherent superposition of circular polarization states, if measured in the vertical/horizontal linear polarization basis, they must be in the same vertical or horizontal polarization state, and in the 45° left or right linear polarization basis, they must be in the same 45° left/rig ht polarization state. Classically, such a polarization correlation condition could in principle exist in some particular polarization basis but not in all of the many possible polarization bases simultaneously. This is the underlying physics of the Bell Inequalities (Reference 8), which deal with the falloff rate of the correlations as the polarization basis of one of the measurements is rotated in angle. The Bell Inequalities demonstrate mathematically that the predictions of sem i-classical local hidden-variable theories are inconsistent with those of standard quantum mechanics. Tests of such polarization correlations have been the basis for a number of Bell-Inequality tests (or so-called EPR experiments), in which the validity of the predictions of quantum mechanics and the inadequacies of semi-classical local hidden-variable theories have been demonstrated to high statistical precision (Reference 1, 2) . It was later demonstrated (Reference 5, 6) that the issues surrounding a violation of the Bell Inequalities could be separated into violations of either parameter independence (the outcome probability of a measurement on one of a pair of entangled particles is independent of the choice of parameters of a measurement performed on the other member of the entangled pair) and violations of outcome independence (the outcome probability of a measurement on one of a pair of entangled particles is independent of the outcome of a measurement performed on the other member of the entangled pair). The observation of a violation of the Bell Inequalities indicates a violation of either parameter independence or outcome independence (or both). Outcome independence is fairly evident in the quantum formalism, while parameter independence is more elusive and depends on specific assumptions. Below, the UNCLASSIFIED/ /rOR. 0rr1e11et U:!I! OHL I 1
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