DOW-UAP-D133, AAWSAP DIRD, The Space Communication Implications of Quantum Entanglement and Nonlocality, March 2010

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The Space-Communication Implications of Quantum Entanglement and Nonlocality Prepared by: Acquisition Support Division (DW0-3) Defense Warning Office Directorate for Analysis Defense Intelligence Agency AAP Person 76 Administrative Note COPYRIGHT WARNING: Further dissemination of the photographs in this publication is not authorized. This product is one in a series of advanced technology reports produced in FY 2009 under the Defense Intelligence Agency, Defense Warning Office's Advanced Aerospace Weapon System Applications (AAWSA) Program. Comments or questions pertaining to this document should be addressed to !AAP Person 1 AAWSA Program Manager, Defense Intelligence Agency, ATTN: CLAR/DWO-3, Bldg 6000, Washington,

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Foreword and Introduction ....................................................................................iv I. Quantum Entanglement, Nonlocality, and EPR Experiments ............................... 1 II. The Quantum No-Signal Theorems .................................................................... 4 III. Nonlocality Versus Special Relativity? ............................................................. 5 IV. Momentum Domain Entanglement and EPR Experiments.................................. 5 VI. Nonlocal Communication Versus Signaling ..................................................... 11 VII. A Transactional Analysis of the Nonlocal Communication Test ...................... 13 VIII. Superluminal and Retrocausal Nonlocal Communication ............................. 17 IX. Paradoxes and Nonlocal Communication ........................................................ 18 XI. Example: Real-Time Earth Control of Mars Rover............................................ 20 XII. Another Superluminal Possibility: Nonlinear Quantum Mechanics................. 22 Figure 1. Schematic of the 1972 Freedman-Clauser Experiment ............................ 2 Figure 2. Schematic of the 1995 Ghost Interference Experiment of the Shih Figure 3. Ghost Interference Position Distributions at X2 ....................................... 7 Figure 4. "Unfolding" the Ghost Interference Experiment...................................... 8 Figure 5. Schematic of the 1998 Dopfer Experiment .............................................. 9 Figure 7. Slit-Imaging Coincidence-Free Version of the Ghost Interference Experiment to Demonstrate Nonlocal Communication ........................... 12 Figure 8. Transactional Interpretation Diagrams for Case 1................................. 15 Figure 9. Transactional Interpretation Diagrams for Case 2................................. 16

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Figure 10. Slit-Imaging Coincidence-Free Version of the Ghost Interference Experiment Demonstrating Superluminal and Retrocausal Signaling .. 17 Figure 11. A Superluminal Nonlocal Communication System in Which the Figure 12. Schematic of Earth-to-Mars Real-Time Control of a Rover................... 21

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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 limitations 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

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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 _fodolsky 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