Acceleration Disrupts Quantum Teleportation

Acceleration disrupts quantum teleportation, a new study has shown (Paul Alsing, University of New Mexico, 505-277-9094). In quantum teleportation (see PNU #350), researchers create a pair of particles (such as photons) and cause them to interact so their properties become interrelated (a process called "entanglement").

Subsequently, after the particles go their separate ways, one can send the first particle of the entangled pair and a new, third particle to a detector simultaneously, and make a "joint" measurement of the particles' properties (such as the directions their electric fields are wiggling). Measuring these particles disturbs them, so as to reduce the amount of information that an experimenter can obtain about their properties. The measurement therefore produces just a limited amount of ordinary, "classical" information.

But since the two entangled particles are interlinked, the measurement also affects the properties of the second, remote particle in the entangled pair. This "nonlocal" effect can be understood as a transfer of "quantum" information from the first to second particle.

When the experimenter who handled the first particle contacts the experimenter handling the second particle with the limited "classical" information that he or she obtained from the measurement (a process that can take place only at light speed or slower), the latter experimenter has enough information to manipulate the second particle in just the right way as to produce the exact quantum properties of the (now destroyed) third particle.

This process of transference of quantum properties between particles, by means of quantum measurement and classical communication, even if the particles are light years apart, is called quantum teleportation, and intimately relies upon the fact that the pair of particles are interlinked or "entangled" through the unusual rules of quantum physics. Quantum teleportation is different from Star Trek teleportation in that real-life physicists are only teleporting a particle's properties, rather than the particle itself.

Drawing from the example above, a new analysis has shown that quantum teleportation would malfunction if the receiver of the second particle is accelerating relative to the third particle. (Coincidentally, spaceships in Star Trek usually don't teleport crew members when they accelerate into warp drive.)

The disruption to quantum teleportation arises from the Davies-Unruh effect (see Physical Review Focus article), in which acceleration, even in empty space, creates a bath of hot particles resulting from the energy of the acceleration. This thermal bath of particles inextricably disrupts the receiver's ability to perfectly recreate (with the second accelerated particle) the properties of the third (unaccelerated) particle that have been teleported from the sender.

While this effect is small for typical accelerations in Earthly labs the result shows an interesting relationship between the effects of space-time motion and the quantum world. (Alsing and Milburn, Physical Review Letters, 31 October 2003)