Super-Cold Atoms

What happens to a gas when cooled to nearly absolute zero  

More than 70 years ago, Albert Einstein, extending work by the Indian physicist Satyendra Nath Bose, predicted that at extremely low temperatures gaseous atoms of certain elements would merge or condense to form a single entity and a new form of matter. Unlike ordinary gases, liquids, and solids, this supercooled substance, which was named a Bose-Einstein condensate (BEC), would contain no individual atoms because the wave functions of the original atoms would overlap one another, leaving no space in between. 

Einstein s hypothesis inspired an international effort to produce the BEC. But, as sometimes happens in science, the necessary technology was not available until fairly recently, and so early investigations were finitless. Lasers, which use a process based on another of Einstein s ideas, were not designed specifically for BEC research, but they became a critical tool for this work. 

The figure shows the Maxwell velocity distribution of the Rb atoms at this temperature. The colors indicate the number of atoms having velocity specified by the two horizontal axes. The blue and white portions represent atoms that have merged to form the BEC. 

Within weeks of the Colorado team s discovery, a group of scientists at Rice University, using similar techniques, sue-ceeded in producing a BEC with lithium atoms, and in 1998 at the Massachusetts Institute of Technology were able to 

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Bose-Einstein condensate (BEC) A super-cold, super-slow moving clump of atoms considered a unique state of matter by some scientists. 

At such cold temperatures, atoms start to do strange things. This state of matter is called a condensate because it is formed by a sort of condensation of atoms. Under normal temperatures, atoms exist in their own bit of space. Near absolute zero, these atoms condense and clump together and form what scientists call a super atom. 

What is usually observed when metal atoms are codeposited with excess organic solvents at -196°C is the formation of a frozen matrix where the atoms are isolated and weakly solvated. Upon warming atoms begin to migrate in the cold liquid phase, and thousands of atoms cluster into particles of 4-9 nm. Continued warming and/or solvent evaporation leads to flocculation (without amalgamation) of these "monomer" clusters into super clusters or chains, and eventally yielding powders(29) or films(32-34). 

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