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Scientists manage 'Star Trek'-like feat
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NEW YORK (December 10, 1997 5:36 p.m. EST) -- Scientists have pulled off a
startling trick that looks like the "Beam-me-up-Scotty" technology of
science fiction. In an Austrian laboratory, scientists destroyed bits of
light in one place and made perfect replicas appear about three feet away.

They did it by transferring information about a crucial physical
characteristic of the original light bits, called photons. The information
was picked up by other photons, which took on that characteristic and so
became replicas of the originals.

The phenomenon that made it happen is so bizarre that even Albert Einstein
didn't believe in it. He called it spooky.

In addition to raising the rather fantastic notion of a new means of
transportation, the trick could lead to ultra-fast computers.

The experiment is reported in Thursday's issue of the journal Natureby
Anton Zeilinger and colleagues at the University of Innsbruck in Austria.
Another research team, based in Rome, has done similar work and submitted
its report to another journal.

The work is the first to demonstrate "quantum teleportation," a bizarre
shifting of physical characteristics between nature's tiniest particles, no
matter how far apart they are.

Scientists might be able to achieve teleportation between atoms within a
few years and molecules within a decade or so, Zeilinger said.

The underlying principle is fundamentally different from the "Star Trek"
process of beaming people around, but could teleportation be used on
people? Could scientists extract information from every tiny particle in a
person, transfer it to a bunch of particles elsewhere, and assemble those
particles into an exact replica of the person?

There's no theoretical problem with that, several experts said. But get real.

"I think it's quite clear that anything approximating teleportation of
complex living beings, even bacteria, is so far away technologically that
it's not really worth thinking about it," said IBM physicist Charles H.
Bennett. He and other physicists proposed quantum teleportation in 1993.

There would just be too much information to assemble and transmit, he and
others said. Even if it were possible someday, it would be so expensive
that "probably it's just as cheap to send the real person," said Benjamin
Schumacher of Kenyon College in Gambier, Ohio.

Besides, Schumacher said, teleportation would "kill you and take you apart
atom by atom so you could be reassembled at the other end, one hopes. It
doesn't seem like a good idea to me."

Much more likely, experts said, is using teleportation between tiny
particles to set up quantum computers. These devices would use
teleportation to sling data around, and they could solve certain complex
problems much faster than today's machines.

In the new work, scientists transferred the trait of "polarization" between
photons. Light behaves like both a photon particle and as a wave. A light
wave has peaks and troughs like an ocean wave, and polarization refers to
the directions in which these peaks and troughs point. Photons retain this
trait.

To transfer the polarization between photons, the researchers used a
phenomenon called entanglement, which a disbelieving Einstein derided.
Since then, however, it's been shown to be real.

When two photons are entangled, "they have opposite luck," said IBM's
Bennett. Whatever happens to one is the opposite of what happens to the
other. In particular, their polarizations are the opposite of each other.

Here's how the Austrians took advantage of that:

Call three photons A, B and C, and assume the goal is to transmit A's
polarization to C. The researchers created B and C as entangled photons.
Then they entangled B with A.

That second step destroyed A, but not before B took on the opposite of A's
original state. This change meant B's entangled partner, C, had to change
polarization to remain the opposite of B's. So C's polarization ended up
the same as A's used to be. The polarization was transmitted.

The process worked only 25 percent of the time because of how the
experiment was set up. It's possible to go to 75 percent and scientists
will shoot for that, Zeilinger said.

If the notion of entanglement leaves your head spinning, don't feel bad.
Zeilinger said he doesn't understand how it works either.

"And you can quote me on that," he said.


By MALCOLM RITTER, AP Science Writer
Copyright 1997 Nando.net
Copyright  1997 The Associated Press
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