Atom Optics Technologies Could be
Phenomenal Source: University of Arizona February 1, 2001
Forty years after the invention of the laser, we carry
around compact disk audio players.
Twenty years after the advent of fiber optics, we
connect on the Internet.
No one's sure yet where atom optics will lead -- but the
possibilities border on fantastical.
Most of us think of optics as using matter in the form
of mirrors and lenses to direct and manipulate light. Atom optics
reverses the roles of matter and light - it uses laser light to direct
and manipulate beams of atoms, or "matter waves."
When in 1993 Pierre Meystre and his colleagues at the
University of Arizona predicted that it is possible to combine beams
of atoms just as beams of laser light are mixed to form a new laser
light beam, "it sounded crazy," he admitted.
Then in March 1999, Nobel Prize winner William D.
Phillips and his group at the Commerce Department's National Institute
of Standards and Technology proved in experiments how it can be done.
They coaxed ultra cold atoms into three separate waves analogous to
laser-like light, then combined them to create a new, fourth wave.
It proved that "nonlinear" systems -- where system
output is not proportional to system input -- applies in atom optics.
"Suddenly, everything we predicted worked, which was
amazing," Meystre said. "Funding for research on ultra cold atoms -
which is what this is all about - is just exploding."
Meystre is Chair of Quantum Optics at the Optical
Sciences Center, and professor of optical sciences and professor of
physics at UA. His forthcoming book, "Atom Optics," (Springer Verlag,
2001) will be the first published on that subject.
Louis-Victor, Prince de Broglie, first postulated the
concept of atoms as waves in 1924. Just as light behaves both as waves
or particles (photons), de Broglie posited, so matter must behave as
particles (atoms) or waves (matter waves, or de Broglie waves).
This particle/wave duality may be one of the most
"unsettling" aspects of quantum mechanics, Meystre said in a lecture
he gave in Germany as an Alexander von Humboldt Prize winner in 1997.
Only in the past decade have scientists been able to
study the wave properties of whole atoms in any detail. That's because
atoms must be chilled to almost absolute zero (zero Kelvin), where
they are slowed almost to a dead stop, before they clearly exhibit
their wave-like nature.
In the past five years scientists have discovered how
with laser light to cool atoms to one millionth of a degree Kelvin.
That's about one billion times colder than room
temperature and one million times colder than interstellar space,
Meystre noted.
"At these extreme temperatures, the world is an utterly
strange place where our everyday common sense is useless, quantum
physics rules with its counterintuitive laws, and atoms behave as
waves," he said. "At these temperatures, the wavelength of atoms
becomes as long or longer than visible light wavelengths."
Scientists already have demonstrated basic atom optical
elements such as atomic mirrors, atomic beam splitters and atomic
gratings. They also have developed crude atom lasers, a device that
pulses individual atoms into a coherent beam of atoms in a single
quantum state. (All atoms in a single quantum state execute the same
motion.)
More practical atom lasers could lead to applications in
precision nanofabrication, atom holography, and "undreamed of
applications that will come as surprises," Meystre predicts.
"We have this vision for atom optics, which is
integrated atom optics -- atom optics on a chip," he said. "One
problem with current atom optics experiments is that they are really
quite big. They take up a couple of tables in the laboratory. The big
push is to do atom optics on the cheap, as
electronics is done on the cheap," by guiding atoms with magnetic and
electrical fields in something the size of an electronic chip.
Atom holography is another stunning idea. Instead of
making an image in light as done in conventional holography, atom
optics would make the hologram of atoms.
"What this means is, we could make a real, 3-dimensional
replica of some object. We could copy objects." Meystre said.
"All of the individual steps to do this with nonlinear
atom optics have been demonstrated. It's just a matter of making it
work all together. I think it will happen in the next two or three
years."
Quantum computing, quantum cryptography, and atom
lithography are other possible technologies that depend on reaching a
deeper theoretical understanding of the fundamental physics that
governs how ultra cold atoms behave.
This kind of fundamental physics is Meystre's research
forte.
The Army, the Office of Naval Research, the National
Science Foundation, and, most recently, NASA have awarded Meystre and
his colleagues hundreds of thousands of dollars in new research money
in the past year.
The most major new grant, from the Department of
Defense, established a 5-year, $5 million research consortium of
Harvard, MIT, Stanford, UA and Yale to develop novel high technology
sensing devices that will make current state-of-the-art sensors used
for strategic navigation, guidance, detection
and mapping obsolete.
Meystre and UA optical sciences Professor Ewan Wright
collaborate in the consortium with other leading U.S. scientists who
are pioneering atom optics, including Stanford's Steven Chu, who won a
1997 Nobel Prize for developing techniques to cool and trap atoms with
laser light.
Future "matter wave sensors" could include a new class
of compact atom-laser gyroscopes at least a million times more
sensitive than current laser gyroscopes and ultra-sensitive
gravity-measuring sensors for detecting underground tunnels and
chambers or undiscovered oil and mineral deposits.
In his newest research project, funded weeks ago by the
NASA Office of Biological and Physical Research, Meystre will study
how atom optics would work in the microgravity of space.
The ultracold atoms used in atom optics are so
slow-moving that gravity pulls them to Earth. Magnetism can be used to
keep beams of atoms from falling down, Meystre said, but magnetism and
electrical fields change the properties of the atoms and degrades the
"coherence," or you might say the "cleanness," of atom beams.
Atom holography and atom lithography for nanoscale
manufacturing (smaller than a billionth of a meter) and inertial
sensors that would be billions of times more sensitive than
counterpart optical devices for navigation, tracking and guidances are
examples of atom optics applications that would
best be done in microgravity.
http://www.optics.arizona.edu/meystre/
by Pierre Meystre
pierre.meystre@optics.arizona.edu
520-621-4651
http://www.optics.arizona.edu
http://www.optics.arizona.edu/Research_Programs/Laboratories/laborator
ies_for_quantum.htm