[extropy-chat] Teleporting an atom

[John K Clark]

They've teleported a photon of light before but in today's Nature there is a
report on teleporting an atom for the first time, this is an article in the
New York Times about it.

John K Clark    jonkc at att.net
==========================

Scientists Teleport Not Kirk, but an Atom

By KENNETH CHANG

Published: June 17, 2004


And the beryllium atom said to the Starship Enterprise, beam me up!

Two teams of scientists report today that for the first time they have
teleported individual atoms, taking characteristics of one atom and
imprinting them on a second.

In physics, teleportation means creating a replica of an object, or at least
some aspect of it, at some distance from the original. The act of
teleporting always destroys the original - not entirely unlike the
transporters of the "Star Trek" television shows and movies - so it is
impossible produce multiple copies.

The prospect of using teleportation to move large objects or people remains
far beyond the current realm of possibility. But it could prove an important
component of so-called quantum computers. Scientists hope that one day such
computers will tap quantum mechanics to solve complex problems quickly by
calculating many different possible answers at once; computers today must
calculate each possibility separately.

The two teams, one at the National Institute of Standards and Technology in
Boulder, Colo., and one at the University of Innsbruck in Austria, worked
independently, but the experiments were similar, using a process proposed by
Dr. Charles H. Bennett, a scientist at I.B.M., and others in 1993.

"This will be an important part of attempts to build quantum computers,"
said Dr. H. Jeff Kimble, a professor of physics at the California Institute
of Technology. He co-wrote a commentary accompanying the two research papers
on the experiments, which appear today in the journal Nature.

"This is a complicated thing that begins to work," Dr. Kimble said. "We've
reached this point on our journey and it's really quite significant."

Several scientific groups, including one led by Dr. Kimble, previously
teleported photons, and scientists at the University of Aarhus in Denmark
reported in 2001 that they had teleported the magnetic field produced by
clouds of atoms.

In the new experiments, both teams of scientists worked with triplets of
charged atoms trapped in magnetic fields. The Colorado team used beryllium;
the Innsbruck researchers used calcium.

The feat of teleportation is transferring information from atom A to atom C
without the two meeting. The third atom, B, is an intermediary.

The three atoms can be thought of as boxes that can contain a 1 or a zero, a
bit of information like that used by a conventional computer chip. The
promise of quantum computers is that both a zero and a 1 can exist at once,
just like the perplexing premise described by the Austrian physicist Erwin
Schrödinger in which a cat in a box can be simultaneously alive and dead
until someone looks inside.

First, atoms B and C were brought together, making them "entangled" and
creating an invisible link between the two atoms no matter how far apart
they were. Atom C was moved away. Next, A and B were similarly entangled.

Then the scientists measured the energy states of A and B, essentially
opening the boxes to see whether each contained a 1 or a zero. Because B had
been entangled with C, opening A and B created an instant change in atom C,
what Albert Einstein called "spooky action at a distance," and this, in
essence, set a combination lock on atom C, with the data in A and B serving
as the combination.

For the final step, the combination was sent and a pulse of laser light was
applied to atom C, almost magically turning it into a replica of the
original A. Atom A was teleported to atom C.

"It's a way of transferring the information," Dr. Rainer Blatt, leader of
the Innsbruck team, said.

A quantum computer could use teleportation to move the results of
calculations from one part of the computer to another. "Teleportation in
principle could be done pretty quick," said Dr. David J. Wineland, head of
the Colorado team, noting that directly moving atoms containing intermediate
results would almost certainly be too slow.

In the current experiments, the teleportation distances were a fraction of a
millimeter, but in principle, the atoms could be teleported over much longer
distances. The teleportation was also not perfect, succeeding about
three-quarters of the time.

"We're not doing very well yet," Dr. Wineland said. "All of these operations
have to be improved."

Teleporting a much larger object, like a person, appears unlikely, if not
entirely impossible, because too much information would have to be captured
and transmitted.

"It's certainly not useful for any beaming in the 'Star Trek' sense," Dr.
Blatt of the University of Innsbruck said. "Consider even some molecules or
something small like a virus. I cannot imagine it. As far as I can see, it's
not going to happen."



-------------- next part --------------
A non-text attachment was scrubbed...
Name: spacer.gif
Type: image/gif
Size: 45 bytes
Desc: not available
URL: <http://lists.extropy.org/pipermail/extropy-chat/attachments/20040617/d6cd0833/attachment.gif>