Defense Intelligence Reference Document The Space Communication Implications Of Quantum Entanglement

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paper attempts to address these questions by taking a close look at quantum
entanglement, quantum nonlocality, the experiments that have explored them,
and proposed experiments to test the causal and faster-than-light
communication issues evoked by such physics.
Quantum entanglement describes the condition of separated parts of the same
quantum system in which each of the parts can be described only by
referencing the state of other parts. This is one of the most counterintuitive
aspects of quantum mechanics, because classically one would expect system
parts out of "local" contact to be completely independent. Thus, entanglement
represents a kind of quantum "connectedness" in which measurements on one
isolated part of an entangled quantum system have nonclassical consequences
for the outcome of measurements performed on the other (possibly very
distant) part of the same system. This quantum connectedness acting in
entangled quantum systems is called quantum nonlocality.
Nonlocality was first highlighted by Albert ~instein and his coworkers Boris
.e_odolsky and Nathan Rosen in their famous EPR paper (Reference 4). They
argued that the nonlocal connectedness of quantum systems was unphysical
in that it implied a faster-than-light connection in apparent conflict with
special relativity. Despite their objection, quantum nonlocality has now been
demonstrated (see Section I) in many quantum systems (Reference 1, 2). In
the physics community, it is now generally acknowledged to be implicit in the
quantum formalism as applied to entangled systems, although there remain a
few Copenhagen "holdouts" who would require an explicit demonstration of
nonlocal signaling before admitting that nonlocality can be considered a real
quantum phenomenon.
The question investigated in this paper is whether quantum nonlocality is the
private domain of nature or whether it can be used in experimental situations
to send signals from one observer to another. As we will see, there is at
present no compelling answer to this question. However, it is clear that if such
nonlocal observer-to-observer communication were possible, it would have
far-reaching implications. In particular, it would represent an enabling
technology for superluminal (and retrocausal) signaling and communications,
and perhaps make possible the real-time exploration of the universe.
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