Physic's 'Holy Grail' finally captured.

A team of physicists in Colorado has done something really cool.

The scientists chilled rubidium-87 atoms to a temperature of 170 nanokelvins, then watched them coalesce into a Bose-Einstein condensate--a state of matter predicted over 70 years ago but never observed until now.

For 15 years, groups around the country have been striving to create such a condensate. The team that finally succeeded included Eric A. Cornell of the National Institute of Standards and Technology, Carl Wieman of the University of Colorado, and their colleagues at the Joint Institute for Laboratory Astrophysics (JILA), all in Boulder. They report their finding in the July 14 Science.

In 1924, Albert Einstein and Indian physicist Satyendra Nath Bose independently predicted that at sufficiently low temperatures, atoms in a dilute, noninteracting gas would condense to the point where they fall into the same quantum state, essentially behaving like a single atom.

Similar conditions prevail in a laser, where photons travel in a coordinated way, generating a coherent light beam. The existence of the atomic condensate opens up the possibility of creating the "atom equivalent of a laser" one day, says Steven Chu of Stanford University, a pioneer in the field.

Cornell's group coaxed the atoms into forming the condensate with a kind of tag-team approach, using two proven techniques. First, by trapping the atoms in a pattern of interfering light waves woven by a system of six lasers, they dropped the temperature to a frigid 20 microkelvins.

Then, with the laser trap switched off, they turned on a magnetic trap that allowed the warmer atoms to escape, taking their excess energy with them.

Along the way, the group developed a magnetic trap that reined the atoms in for a longer time.

The condensate eventually reached a record low of 20 nanokelvins. Images displaying the atoms' velocities began to show a clear peak around zero, indicating a stationary cluster of atoms. When the team removed the magnetic trap, Cornell says, the condensate fraction retained its original elliptical shape, while the uncondensed atoms spread out.

"It wasn't some sort of thermal effect," Cornell says. "It was very consistent with it having a single wave function that has particular properties."

Although many people have been trying to create a Bose-Einstein condensate, no one was sure what they would see once they achieved it.

"When I saw the results, they were breathtaking," said Daniel Kleppner of the Massachusetts Institute of Technology, whose group first developed magnetic cooling techniques. "It's rare that one finds an important new phenomenon which is really so vivid. When you saw it, you just had to believe it--like someone came out ringing a loud bell."

The JILA group plans next to perform spectroscopy on the condensate to see which wavelengths of light it absorbs. "There are six or seven recent theoretical papers about how light should interact with the condensate, and they don't all agree," Cornell says. "We're going to go in and sort that out experimentally."

The race may be won, but the work is far from over.