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For use with Chapter 27
Quantum Theory
Beam Me Up!
Posted April 28, 2000
Teleportation has always been a dream of science fiction writers. However, experiments are now being done in quantum physics that have made teleportation a reality--at
least at the quantum level. Scientists have been able to teleport particles of light called photons.
In the case of such "quantum teleportation," the photon moves from one point in space to another instantly. This may seem to contradict Einstein's Theory of Relativity,
which states that nothing can go faster than the speed of light. Quantum teleportation, however, doesn't break this rule - it goes around it. The photon doesn't actually travel across
the space. Instead, it disappears from one place and reappears in another instantaneously.
This works because two particles (in this case, photons) can be linked together, a process known as "entanglement." When this happens, both particles take on the exact
same quantum properties. They become identical in every way. When the properties of one particle changes, the other changes along with it. And this happens at exactly the same time,
even if the two particles are hundreds of light years away.
A third particle can be introduced into the system and compared to one of the entangled particles. When the third particle causes a change in one of the entangled
particles, the other entangled particle goes through an identical change. The third particle can then be replicated at the second location. Because entangled particles change at the
exact same time, the teleportation is also instantaneous.
Although the change in the entangled particles is instantaneous, the entire process may still be limited by the speed of light. Quantum teleportation is only accurate
25% of the time. To compensate for this, a message must be sent between teleportation points that confirms the accuracy - and this is still limited by standard methods of communication.
While these experiments are ground-breaking, don't start expecting to see Star Trek transporter beams any time soon. Teleporting a photon is very different from teleporting
a human being. Some scientists even suggest that such a feat would be so complicated that it will never be accomplished. Other scientists just see it as a matter of time.
Activity
Use the sources given here to learn more about teleportation. In your science journal, write a science fiction story about teleportation. Be sure to include
the scientific theories behind it and how it is possible.
References
- Quantum Teleportation. Scientific American, April 2000.
- Quantum Teleportation. http://www.research.ibm.com/quantuminfo/teleportation/
- C.H. Bennett, G. Brassard, C. Crepeau, R. Jozsa, A. Peres, and W. Wootters, "Teleporting
an Unknown Quantum State via Dual Classical and EPR Channels", Phys. Rev. Lett. vol. 70, pp 1895-1899 (1993)
(the original 6-author research article).
- Tony Sudbury, "Instant Teleportation", Nature vol.362, pp 586-587 (1993) (a semipopular account).
- Ivars Peterson, Science News, April 10, 1993, p. 229. (another semipopular account).
- Samuel Braunstein, A
fun talk on teleportation
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