J ILA physicists have achieved a temperature far lower than has ever been produced before and created an entirely new state of matter predicted decades ago by Albert Einstein and Indian physicist Satyendra Nath Bose. Cooling rubidium atoms to less than 170 billionths of a degree above absolute zero caused the individual atoms to condense into a "superatom" behaving as a single entity.

JILA is jointly operated by NIST and the University of Colorado at Boulder. Results of the experiment were published in the July 14 issue of Science.

Before photographing the superatom with a laser system, the physicists cooled the atoms to 20 billionths of a degree above absolute zero, the lowest temperature ever achieved. (Absolute zero, -273.15 C, is the theoretical point at which all atomic motion stops.) In the three dimensional graphic view above, color represents density; red is the least dense, followed by yellow, green, blue and white. As the temperature within the JILA atomic trap dropped, the rubidium atoms condensed from their normal state in the graphic on the far left to the blue-white "superatom" on the far right. The "superatom" is about 20 microns in diameter, or about one-fifth the thickness of a sheet of paper.

The trick to creating the superatom was to get a high enough density of atoms at a cold enough temperature. The JILA apparatus includes six diode lasers that slow the room temperature atoms down and an unusual magnetic trap that kicks the hottest atoms out of the trap, while preventing the coldest atoms from leaving.

The 2,000 rubidium atoms forming the condensate are in a strange condition, existing in a kind of smeared-out, overlapping stew. While many theories have been offered, most of the experimental properties of the condensate are still a big unknown. The JILA researchers hope that superatoms will provide physicists with a new way to study quantum effects on a large scale.

Contact: Eric Cornell, (303) 492-6281 or Carl Wieman, (303) 492-6963.