Defense Intelligence Reference Document The Space Communication Implications Of Quantum Entanglement

UNCLASSIFIED//F81il 8FFHil.tzk Wili 8HkY
The Space-Communication Implications of Quantum
Entanglement and Nonlocality
Foreword and Introduction
This paper reviews quantum entanglement and nonlocality and considers the
possibility that this phenomenon could be used for sending observer-to-
observer signals. Such a demonstration would break several quantum "no-
signal theorems" in the physics literature. Nonlocal quantum signaling would
have far-reaching implications as an enabling technology for superluminal and
retrocausal signaling. Scenarios that might lead to nonlocal quantum
communication are described, and applications to retrocausal signaling and
real-time space communication are considered. Also considered briefly is the
nonlocal communication implications of nonlinear quantum mechanics.
Communication in space at the scale of the solar system is severely limited by
the space-time scale set by the speed of light. Light signals, whether in the
form of radio waves, microwaves, visible light, X-rays, or gamma rays, require
about 3.3 microseconds to travel a distance of 1 kilometer. A light signal sent
from Earth requires about 1.3 seconds to reach the Moon, between 4.4 and 20
minutes to reach Mars, and between 4 and 4.3 hours to reach Neptune,
depending on their orbital positions. This time delay makes real-time control
of remote space-based devices impossible and leads to the need for pre-
programmed robotic devices with enough "intelligence" to perform limited
operations with a minimum of remote control.
The burden of these Ii mitations raises the question of whether there is some
way to speed up the space communications link. The conventional answer is
"No!," because the well-established special theory of relativity is viewed as
limiting signal transmission speed to the speed of light, with superluminal
communications strictly forbidden. However, as will be discussed in Section
III, relativity prohibits only certain forms of superluminal communication,
while other forms are not in conflict with relativity. One phenomenon that
appears, at least superficially, to exhibit superluminal aspects while
preserving compatibility with special relativity is quantum nonlocality, the
ability of quantum phenomena to enforce correlations between quantum
states over large separations in space-time.
When two photons emerge from a single quantum event, the state of one
photon may be subtly connected to that of the other. The classical view is that,
once separated, such photon states must be fixed according to mechanics and
conservation relations that act at the point of their origin, so that modifying
one later will not affect the other. In quantum physics, however, as borne out
by experiment (Reference 1, 2), the outcome of a measurement of the state of
one of the photons, even well after their point of joint creation, can affect the
state of the other photon. This connection is referred to as quantum
entanglement, a phrase first coined by Erwin SchrOdinger (Reference 3).
Questions raised by the phenomenon of quantum entanglement are: (1) what
is the causal connection between entangled states, and (2) can the
phenomenon possibly be used for sending observer-to-observer signals? This
iv
UNCLASSIFIED/ ,'f81il 8ffl@Itllt ~:!I! 8HLY