Getting atoms to march one by one

Scientists at the National Institute of Standards and Technology (NIST) outlined, in a recent issue of Applied Physics Letters, a new way of harnessing neutral atoms in a vacuum chamber by sending them past laser beams tuned to a frequency that particular atoms can easily absorb. With the laser energy absorbed, the atom's energy state drops, and the atom falls into the chamber.

So far, that's nothing new--the NIST scientists acknowledge that such a "magneto-electrical trap" has been devised before. But in their article, "Atoms on demand: Fast, deterministic production of single Cr atoms," the researchers claim to have advanced the technique by figuring out a way to monitor and regulate the number of atoms in the chamber at any given time, paving the way to work with atoms one at a time.

"Getting a single, constantly moving atom to go exactly where you want it to is a difficult scientific challenge," NIST wrote in a statement. The new method, the institute said, is "likely to warm the hearts of researchers in fields ranging from nanotechnology to quantum computing to semiconductor processing."

The field of nanotechnology, which has captured the imagination of the computing industry, involves working with materials at the atomic or molecular level, with the goal of making products out of components measuring 100 billionths of a meter or less. Much attention recently has gone to carbon nanotubes, but chipmakers have produced standard processors, like Intel's Prescott, using a 90-nanometer process.

Scientists in the corporate sector welcomed the news of the government's tests, but cautioned that the work remains in the realm of basic science, with practical applications still beyond the horizon.

At this stage of nanotechnology research, as semiconductor and nanoelectronics efforts approach atomic dimensions, much of the challenge lies in determining how matter behaves at tiny sizes.

"I think scientifically it's significant," said H. Kumar Wickramasinghe, an IBM fellow and manager of nanoscale and quantum studies at the company's Almaden Research Center in San Jose, Calif. "You use these kinds of experiments to understand basic science. At this point there is no practical application, but you have to have these kinds of tools."

The paper in Applied Physics Letter comes at a high point for the science of very, very small things. The U.S. House of Representatives last week passed the Nanotechnology Research and Development Act, which budgets $2.36 billion over three years for public and private nanotechnology research.

A week before that, IBM and University of Toronto researchers said they had devised a way to get light out of carbon nanotubes, a technique that could benefit the development of fiber-optic technology. And high-tech researchers in February convened in San Francisco to predict that the manipulation of molecules would lead to significant advances in everyday computing.

NIST said the newly devised system had a 99 percent accuracy rate in terms of keeping single atoms in the chamber. The method expels 10 atoms per second, a rate NIST said it hopes to increase. The institute also plans to figure out a method for getting the atoms to "adjacent instrumentation."

In the article, NIST scientists called their work crucial to "an explosion of research involving single atoms, ions and molecules."

"Key to the advancement of this type of research is the development of techniques to controllably produce these isolated quantum objects," they wrote. "To date, the methods employed have relied on creating a sparse, random ensemble and then either hunting for a single particle (e.g., on a surface), or waiting until a single particle is captured randomly. With the present work, we overcome the obstacles imposed by this randomness by demonstrating a source in which a single, cold atom...is available in small volume...essentially whenever it is needed."