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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 8FFI@IAL l!IS! 8HLY The experimenters demonstrated that 300 passing the vertically polarized photon (e) through a double- or single-slit "' 250 system before detection at D1 produced a "comb" interference distribut ion or a C:::, 0 0 Ql 200 "bump" diffraction distribution, respectively, in the position X2 of the (.) C: Ql 'C ·.:; 150 100 horizontally po larized photon (o) detected at D2 when the pair of photons C: ·5 0 so is examined in coincidence. I n other words, the position distribution of the straight-through photon shows patterns ·8 · 6 · 4 · 2 0 2 4 De tec tor 2 position (mm) characteristic of the single- or double slit system through which its tw in entangled photon passed. Figure 3 shows the observed position distributions for the two cases . From the viewpoint of nonlocal commun ication, we note that modifying the slit system before D1 through which the reflected photon passes, wh ich can be thought of as the action of a · 8 · 4 ·2 0 2 4 "sending" observer, nonlocally causes Detector 2 position (mm) an observable change in the Xrposition distribution of the undeflected photon, Figure 3. Ghost Interference Position Distributions as detected by a " receiving" observer at at x, D2. This is a nonclassical effect t hat demonstrates the nonlocal connection between the entangled pa ir and that might form the basis for transmission of a nonlocal signal between the two observers. However, the Ghost I nterference experiment does not, in the form reported, demonstrate nonlocal commun ication, because of its use of a classical communication link in imposing the coincidence requirement between the detected photons. In t heir paper, the authors comment that with the two-slit system in place, in t he absence of coi ncidences there is no observable two-slit interference pattern distributions at either D1 or D2. They attribute this lack of an interference "signal" to the horizontal variation in the creation position of the down-converted photons . The variation is enough to cause the "e" photons to arrive at the two slits with relative path lengths that may differ by more than a wavelength, t hereby randomly shifting and wash ing out any interference pattern. Furthermore, their source of entangled photons was very inefficient and noisy. Only about 1 in 10 10 pump photons produced an entangled pa ir, while many unentang led "noise" photons of the same wavelength were created by fluorescence in the crystal. Therefore, even if the coincidence requirement had been in principle removable (see below), it is not surprising that coincidences were required to observe the reported effects . 0 L__,=..J.----'--~__J_~-----'---~-'--~...,__~~ '---' (a) Two slits "' C:::, 0 0 a, 0 C: Ql ~ C: ·o 0 500 (b) One slit 400 300 200 100 UNCLASSIFIED/ ,'FOR. 8fflE!IJltL U:!E fJHL I 7
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