ROANOKE TIMES
Copyright (c) 1997, Roanoke Times
DATE: Monday, January 27, 1997 TAG: 9701270077
SECTION: NATIONAL/INTERNATIONAL PAGE: A-1 EDITION: METRO
DATELINE: DALLAS
SOURCE: The Dallas Morning News
Physicists have now done to atoms what they did to light a long time ago: They've created a laser beam, this time made of a stream of atoms.
The new ``atom laser'' may someday have applications ranging from building tiny devices to making more precise atomic clocks.
For now, many scientists say that it's not possible to predict what applications will come from the atom laser, just as no one could foresee three decades ago that the newly invented light laser would one day be used in supermarket price scanners and CD players.
The atom laser may be a crucial breakthrough toward controlling atoms at a very precise level, researchers say.
``This discovery is one of the most exciting things I've seen during my career in atomic physics,'' said John Doyle of Harvard University in Cambridge, Mass.
Researchers from the Massachusetts Institute of Technology reported their development of the atom laser in two scientific papers this week. One paper appears in today's issue of Physical Review Letters, and the other will appear Friday in the journal Science.
Physicists have dreamed of making an atom laser for years, but the MIT group is the first to demonstrate one, scientists said.
The hallmark of a laser is that the material it's made of moves in a ``coherent'' beam. In the case of a light laser, this means that the light waves all move in step with one another. The atom laser is made of a beam of atoms marching one after the other.
The light laser and atom laser ``are really two different animals,'' said Randy Hulet, a physicist at Rice University in Houston. The atom laser is made of matter and thus has mass, unlike a traditional laser beam.
Scientists think the atom laser may someday be used to nudge around individual atoms - for example, to deposit atoms directly onto computer chips. Or the new laser may be used to build an even more precise atomic clock, said Michael Andrews, a graduate student at MIT and member of the research team.
Andrews and his colleagues, led by physicist Wolfgang Ketterle, built the atom laser by taking advantage of a new form of matter known as a Bose-Einstein condensate.
First created in 1995, a Bose-Einstein condensate is a mass of atoms that have been squished together under special laboratory conditions. Within the condensate, the atoms take on completely different properties. They stop behaving as single particles and instead behave as one giant entity.
So the atoms in the condensate behave as a single coherent wave - the first step toward making an atom laser. But creating a Bose-Einstein condensate is technically tough. Only a few research groups around the world, including the MIT team and Hulet's laboratory, have been able to make the condensate.
To make the atom laser, the MIT researchers created a condensate of sodium atoms. They then coaxed the condensate to emit a pulsed beam of atoms by switching a magnetic field on and off. Each attempt took researchers at least 20 hours.
When the scientists got their first positive result at 3 a.m. one day last November, they were elated.
``When the picture came onto the computer, we were all giving high-fives,'' Andrews said.
After running other experiments to verify the results, the researchers felt confident enough to announce their new atom laser.
Despite the initial excitement, the scientists say there are several problems to overcome before atom lasers show up in everyday life.
For one thing, researchers must chill the atoms to a few millionths of a degree above absolute zero - the complete absence of heat - to create the condensate. The condensate also must be contained within a vacuum chamber - something not available at the corner grocery store.
Finally, the atom laser must obey the laws of gravity. Unlike a traditional laser beam, which can zap in any direction, the atoms coming from the new laser fall toward the ground because of the pull of gravity.
In fact, the sodium atoms falling out of the new laser look like a dripping faucet, the scientists said.
In the future, the researchers hope to direct the beam by applying forces to push and pull it in different directions.
LENGTH: Medium: 80 linesby CNB