Published: Thursday, January 20, 2000
http://www.pioneerplanet.com/seven-days/2/news/docs/023369.htm
Physicists coax atom to be two places at same time
ASSOCIATED PRESS
Physicists say they have managed to nudge atoms back and forth between our
everyday world and the strange quantum realm where objects can paradoxically
be in two places at the same time.
If physicists can further refine their control over this realm, it could
result in incredibly fast quantum computers able to crack even the toughest
encryption codes now used by conventional computers.
Quantum theory holds that objects on the subatomic level can simultaneously
be in two places or have other
properties that seem contradictory in the everyday world.
Scientists have achieved quantum states. But in an experiment reported in
today's issue of the journal Nature, they were able to move atoms into and
out of quantum states with more precision than before. That kind of control
is necessary if scientists are to come up with practical devices that employ
quantum principles.
For example, a quantum computer could store information in the quantum
states of atoms or molecules instead of in silicon chips. But for such a
computer to work, scientists would have to be able to block the outside
forces that can cause a quantum state to collapse.
David Wineland and fellow researchers at the National Institute of Standards
and Technology in Boulder, Colo., coaxed a beryllium atom in a vacuum to be
in two places at the same time -- the paradoxical ``Schroedinger's cat''
state. The researchers then caused the system to collapse by introducing
contact to the outside world.
Austrian physicist Erwin Schroedinger proposed the cat paradox in the early
20th century. He described the hypothetical situation of a cat in a box with
vial of cyanide gas capped by a decaying radioactive atom, which would
release the poison once it decayed. Under quantum theory, the atom could be
in both states, meaning the cat could be both dead and alive.
The researchers in Colorado said they were able to keep a beryllium ion in a
Schroedinger's cat-like state for as long as as 100-millionths of a second.
To do that, the beryllium atom was cooled to close to absolute zero -- minus
459 degrees -- and isolated from all types of radiation, radio waves and
other energy sources. The researchers then used lasers to force the atom's
single electron into two states of spin, which forced the atom to be in two
places at the same time.
Received on Fri Jan 21 2000 - 23:33:00 PST