Real-life teleportation will never come
close to the teleportation of fiction, but instantly sending single quantum
particles like photons from one place to another has been proved possible
in laboratory experiments.
The ability promises to extend the reach of quantum cryptography,
which offers potentially perfect security.
Researchers from the University of Geneva have moved quantum teleportation
a step forward by instantly transporting qubits -- photons whose properties
can represent a 1 or a 0 -- over six kilometers of optical fiber.
The light pulses that transport information over today's long
distance optical fibers are each made up of billions of photons and the
signals are able to travel long distances only because the pulses are
Quantum cryptography signals cannot be refreshed because copying
them destroys the information they carry. Teleportation is akin to a fax
machine for quantum particles. A pair of photons are entangled, or linked
so that their properties remain in lockstep, and one of the pair is sent
to the receiver. The particle to be transported is brought into contact
with the sender's half of the pair, which destroys the original particle
but in the process turns the receiver's half of the pair into an exact
The quantum relay could span several hundred kilometers. Longer
distances would require quantum repeaters, which require quantum memory.
Researchers are still figuring out how to make quantum memory.
It is too soon to say when quantum relays could be used practically,
according to the researchers. The work appeared in the January 29, 2004
issue of Physical Review Letters.
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