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Physics: Entanglement and Teleportation ("beam me up Scotty")

Connections Through Time,   Issue 22: January - March 2004

"en·tan·gle   v. –tr.  

1. To twist together or entwine into a confusing mass;"

- from the American Heritage Dictionary

Teleportation of Particles: Status by Dr. Nicholas Gisin, Leader of the Group of Applied Physics at Geneva University,  presented on February 4, 2004.
In quantum mechanics (QM), one of the most important and confusing concepts involves "entanglement" of QM particles.  The ordinary English-language definition of entanglement, quoted above, probably captures the QM meaning as well as any non-mathematical definition.

While there is plenty of debate about the meaning of QM and entanglement, physicists have performed laboratory experiments that demonstrate the reality and possible application of this mysterious phenomenon...and you will love one application because it is spooky and yet, real!  Quantum Teleportation of photons (light particles) has been demonstrated in at least two laboratories.

In Star Trek we see the almost instantaneous teleportation of people.  While this may not be possible any time soon,  physicists have successfully teleported photons applying the reality of QM and what Einstein termed 'spooky interactions at a distance'.  This spooky interaction is entanglement - "Entanglement of a pair of objects means that measurements on one will instantaneously change the properties of the other - no matter how far away they areRef".

It was the physicist Charles Bennett from IBM's labs at Yorktown Heights in New York who introduced the world to the idea of quantum teleportation in 1993.  The idea combined entanglement and normal slower than the speed of light communication.   The teleportation does destroy information concerning the original particle, however, this information can be reconstructed, exactly, at the new location.  And the reconstruction, or materialization, does not require the teleported particles to travel the distance in-between!  Quantum teleporting of particles can't happen faster than light, something Einstein would be pleased to learn.

Nine years later, in 2002, the quantum optics group at the Australian National University used entanglement to teleport a laser beam in their laboratory. The experiment itself was extremely complicated being the culmination of a decade of work. This is the second time this effect has been observed, following earlier work at the California Institute of Technology.  The research program is led by Dr. Ping Koy Lam, Prof. Hans Bachor and Dr. Timothy Ralph. The teleportation experiment itself is the PhD project of Mr. Warwick Bowen and involves a team of international experts: Dr. Roman Schnabel (Germany), Dr. Nicolas Treps (France) and Dr. Ben Buchler (Australia).

So, this experiment showed that you do the quantum equivalent of faxing particles within one laboratory by making photons from one location materialize at another.  Larger distances have already been done by researchers at the University of Geneva in Switzerland and the University of Aarhus in Denmark.  They have teleported photons from one laboratory to another lab 55 meters away, and their setup simulated a distance of two kilometers.

"Quantum states, which dictate the ultimate structure of objects, can be teleported," said Nicholas Gisin, a professor of physics at the University of Geneva.  The key to teleportation is that only this information is transported. "Objects can be transferred from one place to another without ever existing anywhere in between.  But only the structure is teleported.  The original object is destroyed and reconstructed," he said.  

Teleportation has numerous possible applications. Perhaps the most promising are in the communication and computer industries. Quantum teleportation could potentially allow fiber optic communication with faster bit transfer rates, and 100% secure encryption of messages, and quantum computers with the ability to crunch complex mathematical problems millions of times faster than present day computers.  We discuss quantum computers in the next section.


Teleporting a Beam of Laser Light

Teleportation goes the distance

From here to there

Quantum Teleportation


Go to another section of this issue:
Intuition: Entanglement and Quantum Computers       Applications: Entanglement and Life

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