Physicists Teleport Quantum Bits Over Long Distance

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Entanglement

Until 1993, scientists considered teleportation impossible because it requires making an exact copy of every atom in an object, which goes against the so-called uncertainty principle of quantum mechanics. According to the principle, the very act of measuring a tiny particle destroys it, so an exact replica can never be made.

Wootters and his colleagues showed that the way around the problem is to rely on the concept of entanglement, an area of physics that Albert Einstein referred to as "spooky action at a distance."

"If two particles are entangled, they act in some respects as if they were a single object," said Wootters. Everything that happens to one of the entangled pairs instantly affects the other, no matter how far apart each of the entangled particles is from the other.

Braunstein likens entanglement to "a pair of ideal lovers who know each other so well that they could answer for their lover even if separated by long distances."

Entangled pairs are made by taking one photon and converting it into a pair that fly off in opposite directions. By imposing the object to be teleported on one member of the entangled pair, the object is instantaneously imposed on the other member of the entangled pair.

That, say the scientists, is quantum teleportation, even though a precise measurement of the object teleported was never made.

Applications

Scientists believe that this technology has practical applications in the field of quantum computing and quantum cryptology, technologies that hold promises for making computing both much faster and secure.

"The possible applications concern communication between future quantum computers and also between gates inside an individual quantum computer," said Anton Zeilinger, a physicist at the University Vienna in Austria who was part of the team that achieved quantum teleportation in 1997.

Wootters explained that the technology could allow computers to send the code to unlock secret messages between each without the fear of another computer intercepting the code or the code deteriorating as it traveled over conventional communications mediums such as a fiber optic wire.

However, Star Trek fans probably have a long wait ahead of them before they will be able to step onto a transporter and be whisked instantaneously to their desired location.

"With today's technology, only very elementary objects can be teleported," said Gisin. "Possibly, larger objects like a molecule will be teleported in my life-time, but really large objects are not teleportable using foreseeable technologies."

Scientists say there is simply too much information in a human that needs to be teleported to make this technology applicable.

"The key thing for now is the sheer amount of information involved," said Braunstein. "Even with the best communication channels we could conceive of at the moment transferring all that info would take the age of the universe."

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