From: Mitchell Porter (mitch@thehub.com.au)
Date: Sun Jan 26 1997 - 23:14:44 MST
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----- Forwarded message from Fred Hapgood -----
From: hapgood@pobox.com (Fred Hapgood)
To: nsg-d@world.std.com
Subject: (fwd) Physicists create first atom laser
Date: Mon, 27 Jan 1997 06:09:36 GMT
From: C-upi@clari.net (UPI / ELIZABETH MANNING)
Newsgroups: clari.tw.science,clari.local.massachusetts,clari.tw.top
Subject: Physicists create first atom laser
Date: Sun, 26 Jan 1997 17:20:51 PST
UPI Science News
WASHINGTON, Jan. 27 (UPI) -- The world's first atom laser which shoots
highly controlled particles of matter rather than light has been built
at the Massachusetts Institute of Technology, physicists reported
Monday.
Experts suggest the achievement may lead to more precise navigation
equipment and machine tools as well as smaller, more efficient computer
chips.
The Cambridge, Mass.-based researchers published their findings in
the current issue of Physical Review Letters and in Thursday's issue of
the journal Science.
Wolfgang Ketterle, senior researcher on the project, described the
discovery as ``exceeding all expectations.'' The laser is based on
predictions made 70 years ago by Albert Einstein and Indian physicist
Satyendra Nath Bose, but no one was sure such a device could ever be
made.
The more familiar photon laser, which shoots particles of light, was
discovered in 1960. Thirty-five years later, its presence is nearly
ubiquitous in grocery scanners, CD players, communications, etching
machines, cosmetic surgery, and other applications.
In contrast, the new laser shoots atoms. Both kinds of lasers,
however, line up the particles into what Ketterle calls ``one coherent
dance.'' They are synchronized in wavelength and phase rather than
randomly flitting around.
The atom laser uses ultracold particles of sodium. At temperatures
more than a million times colder than outer space, atoms lose their
individuality and begin acting as one. This new state of matter, called
Bose-Einstein concentrate or BEC, was first reported in July 1995 by
physicists at the National Institute for Standards and Technology and
the Unversity of Colorado.
``I don't think any of us thought this (atom laser) would happen, if
ever, for at least several years,'' said Randall Hulet of Rice
University in Houston. ``It's a really incredible demonstration.''
Atoms in BEC state require a magnetic trap inside a vacuum chamber to
isolate them from the ``scorching'' temperatures of the everyday world.
The achievement of Ketterle's group was to extract sodium BEC from the
magnetic trap in a controlled fashion and show that they were still
coherent.
Ketterle's graduate student, Michael Andrews, said BEC particles
``all like to be in the same state of motion, or do the same thing''
because even particles of matter share some of the wave-like behavior of
light, radio waves, and other types of energy. Normally, the atoms are
too far apart and their wavelengths are much too small for this
characteristic to noticeably influence them.
But as atoms are cooled to near -460 degrees Fahrenheit (-273 degrees
Celsius) -- called absolute zero, where all motion stops -- their
wavelengths eventually match the distance they are to one another. They
fall into synch, and begin behaving as one entity.
And when particles are coherent, they become highly predictable and
controllable.
What Andrews describes as ``the ultimate control of matter'' will
help physicists better isolate and understand the influences that atoms
experience.
``Atomic clocks are essential for state-of-the-art navigation
systems,'' Andrews said. Global-positioning satellites use these highly
precise timekeepers to pinpoint locations, for example. Ever finer
calibrations will reduce margins of error.
William Phillips of NIST in Gaithersburg, Md., said he currently sees
the best opportunity in nanotechnology. The tiny wavelength of the atom
laser may ``do better writing on permanent structures such as computer
chips,'' he said, packing in more memory or functions on chips of
current technology.
Even nanomachines -- molecular structures with moving parts -- may
cross the threshold from science fiction to reality.
``I don't know how realistic that is, but we're now at the stage
where we can find out,'' Phillips said. ``No one knew what a photon
laser was good for in 1960 either.''
---
Copyright 1997 by United Press International.
All rights reserved.
---
----- End of forwarded message from Fred Hapgood -----
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