Success in slowing down atoms Nobel: Dr. William D. Phillips, a Gaithersburg physicist, was named a co-recipient of the 1997 Nobel Prize in physics for his work in slowing and capturing atoms in laser "traps."

Sun Journal

October 16, 1997|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

The trick to studying speeding atoms is to slow them down to a crawl.

And the trick to slowing them down, it turns out, is to steer them into a stream of carefully tuned laser light moving in the opposite direction.

It's a little like getting a Nobel Prize winner to slow down and talk to you by sending him up a down escalator.

Dr. William D. Phillips, a Gaithersburg physicist, was slowed down by reporters yesterday at a laser conference in Long Beach, Calif., after the announcement that he was a co-recipient of the 1997 Nobel Prize in physics for his work in slowing and capturing atoms in laser "traps."

Phillips, a 48-year-old father of two, said he got the news in a startling 3: 30 a.m. wake-up call from Sweden, which he barely remembers.

"I was sharing a room with one of my colleagues from NIST [National Institute of Standards and Technology]. He didn't get any sleep after that either," he said. Phillips called his wife back home, but "she had already heard it on the radio."

"I really didn't expect to get this," he said. "It's been absolutely wonderful, the kind of thing you dream about."

It was not such a surprise to his colleagues at the National Institute of Standards and Technology in Gaithersburg, where he has been a staff physicist since 1978. Dr. Steven L. Rolston, a member of Phillips' team, said the "buzz" at NIST for several years has been that Phillips was in line for a Nobel Prize.

"I've known over the years and a number of people have known that he's been nominated," Rolston said. "It was not a surprise."

Even so, it was a thrill. "Everyone is very happy here," he said. "I believe this is the first Nobel for NIST."

Phillips will split the $1 million Nobel award with two other researchers who led advances in the same field -- Dr. Steven Chu of Stanford University and Dr. Claude Cohen-Tannoudji of the College de France and the Ecole Normale Superieure in Paris.

The Royal Swedish Academy of Sciences chose Phillips, Chu and theoretician Cohen-Tannoudji because their work in the 1980s developed a novel research technology that opened a new field of scientific study.

Remarkable for its relative simplicity and low cost, it has since become a tool used by many researchers in physics and, increasingly, biology for the manipulation and control of atoms and structures on an atomic scale.

"It's actually become a boom industry in atomic physics," Rolston said. "It's really tabletop physics. It doesn't need a billion-dollar accelerator, so it has become very attractive to faculty members in very small universities. You can do an experiment on a single optical table of 4 feet by 8 feet, and with very small groups."

Physicists trying to study the behavior and structure of atoms and molecules had been stymied by the fact that their subjects refused to sit still, and vanished too quickly from their field of view.

Molecules of air at room temperature, for example, are zipping around and bouncing off each other at speeds of almost 2,500 mph, although their average speed is no more than the ambient breeze.

Even solids, such as a desk, are composed of atoms vibrating at very high speeds, although over very short distances. The hotter the material, the faster the atoms.

Scientists can slow them down by cooling them. But even at minus 270 degrees Celsius -- just a few degrees above absolute zero, the theoretical point at which all atomic motions cease -- hydrogen atoms are still moving at nearly 250 mph.

One reason scientists want to slow down atoms is to measure them more precisely. A good analogy, Rolston said, is a wristwatch.

"Imagine you have a wristwatch and I ask you how well it keeps time," he said. "If I give you 10 seconds to give me that, you can watch it for 10 seconds and compare it" with another timepiece. "If I give you two hours, you can give me a much more precise answer."

Atomic clocks, for example, can be made more precise if they can measure the vibration of cesium atoms for longer periods of time. The next generation of atomic clocks, now in development at NIST, will be 100 times more precise than the current generation thanks to the laser cooling and trapping technologies for which this year's Nobel was awarded.

That has applications in many fields, including communications and navigation. Global positioning systems rely heavily on the precision of atomic clocks.

It was Chu, then at Bell Laboratories in New Jersey, who first found a means of using laser light in a vacuum chamber to slow down atoms. He relied on the understanding that light, although it seems to shine on us without pushing us around, actually does have an impact.

"One of the reasons a comet's tail points away from the sun is due to the force of the light," Rolston said. "It's called radiation pressure. Light carries momentum and can exert a force. That's the fundamental tool we use to slow things down."

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