Historical research guide · 0367 · 2010

DIRD The Space Communication Implications of Quantum Entanglement and Nonlocality

DIA / AAWSAP contractor

In one minute

This is the entry in the Defense Intelligence Agency’s advanced-aerospace reading list that asks whether two entangled particles can carry a message. Its author starts from settled ground: nonlocality is real and measured, from Freedman and Clauser in 1972 through Aspect in 1982 to the Gisin group running entangled photons across 156 kilometres of Swiss telephone fibre. Then he asks the harder question. The textbooks contain no-signal theorems saying you can never use that connection to send anything, and the paper shows that at least some of those proofs quietly assume the answer they reach. He proposes a concrete tabletop test: a slit-imaging version of the ghost-interference experiment in which flipping an optical switch on one photon changes the pattern a camera sees from its twin, with no coincidence counter linking them. If it works, a message could be read before it is sent, and a Mars rover could be driven from Earth in real time. He is candid that the trade-off between coherence and entanglement may be exactly how nature forbids it.

Connection

Chapter 4 is about engineering the metric rather than racing through it, and this paper is the communications half of the same idea: it shows in careful detail why a nonlocal link would not violate Lorentz invariance at all, only causality. For chapter 1’s evidence ladder it is the clearest case in the whole DIRD series of a government report naming the exact bench experiment that would settle a question, and then saying plainly that the result is not yet in.

From the source

Quantum nonlocality is experimentally established: Freedman and Clauser in 1972 excluded local hidden-variable theories by 6.7 standard deviations, the Aspect group in 1982 by 46 standard deviations after closing several loopholes, and the Gisin group demonstrated the nonlocal connection across 156 kilometres of Swiss Telephone fibre between Geneva and Bern.Section I, pp. 1–3
Relativity forbids only those superluminal signals that could establish a fixed simultaneity between two points; because a nonlocal signal is sent at the arrival of one photon and received at the arrival of the other, and both instants are path- and delay-dependent, nonlocal signalling has no conflict with Lorentz invariance — the principle that would be violated is causality, not relativity.Section III, p. 5
At least some of the quantum no-signal theorems are tautological: they assume the measurement process and its Hamiltonian are local, which builds the conclusion of no signalling into the premises, and standard Bose-Einstein symmetrisation in systems of bosons is a counter-example inconsistent with those starting assumptions.Section II, p. 4
Momentum-domain entanglement, not the polarisation domain used in most Bell tests, is the promising vehicle, because an observer can force the photon into wave-like or particle-like behaviour: in the 1995 ghost-interference experiment of the Shih group and in Birgit Dopfer’s 1998 thesis, a change made at one detector nonlocally changes the interference pattern recorded at the other.Sections I and IV, pp. 3–9; Figures 2, 3 and 5
A coincidence-free slit-imaging version of the ghost-interference experiment is specified in full: a lens images one slit pair onto the other so only entangled twins reach both arms, and an optical switch either routes the light to two detectors, giving which-way information, or through a combiner, erasing it — with roughly 100 photon detections per bit, matched 10-kilometre fibre runs would let a message be received about 40 microseconds before it was sent.Sections VI and VIII, pp. 11–17; Figures 7 and 10
The measurement that decides the question is whether a design point exists with enough coherence and enough entanglement at once: the Saleh group showed the two are complementary, so as the source-to-slit distance grows the pattern sharpens while the entanglement fades, and whether there is a workable sweet spot between them is unresolved.Section V, pp. 10–11; Section XIII, p. 23

The way in

https://documents2.theblackvault.com/documents/dia/AAWSAP-DIRDs/DIRD_16-DIRD_The_Space_Communication_Implications_of_Quantum_Entanglement_and_Nonlocality.pdf

Historical source-access record. This guide links to the original; it does not reproduce the paper text.

Defense Intelligence Reference Document, Acquisition Threat Support. DIA-08-1003-016, 30 March 2010 (ICOD: 1 December 2009), produced under the Defense Intelligence Agency Advanced Aerospace Weapon System Applications (AAWSA) Program. Released under FOIA and published by The Black Vault. AUTHOR. Withheld under FOIA exemption (b)(6), and the preparing office under 10 USC 424. Internal evidence points to John G. Cramer of the University of Washington — Section VII analyses the proposed test with the transactional interpretation of quantum mechanics, reference 19 is three of Cramer’s own papers, and the closing line reports that ‘at least one experiment in progress aims to produce a coincidence-free version of the Ghost Interference experiment’, which is the experiment Cramer was then running — but the released copy names no one, so this is an inference and not an attribution. TEXT. Full text below, pages iv to 25, including the glossary appendix and the reference list. The document carries a copyright warning against further dissemination of its photographs, so the twelve figures are not reproduced; their captions are kept because several carry the physics. Greek letters, exponents, degree signs and micro symbols mangled by the scan are restored, detector and slit labels misread as digits (0 for D, 5 for S) are corrected, and the inequality in the space-time interval definition is written with ordinary parentheses so the page renders. A few of the inline reference numbers in the released copy do not match its own reference list; they are reproduced exactly as printed.

How to cite it

DIA / AAWSAP contractor (2010) DIRD The Space Communication Implications of Quantum Entanglement and Nonlocality https://documents2.theblackvault.com/documents/dia/AAWSAP-DIRDs/DIRD_16-DIRD_The_Space_Communication_Implications_of_Quantum_Entanglement_and_Nonlocality.pdf

Where it sits in the curriculum

The reference documents and the institutional record