The Nobel Prize in Physics 2001     
 To the left, Ketterle’s first interference pattern.
The interference pattern between two expanding condensates resembles that formed by throwing two stones into still water.
Large condensates and interference patterns

Wolfgang Ketterle came to the Massachusetts Institute of Technology (MIT) in 1990. He worked with a different alkali atom, sodium, and published his BEC results four months after Cornell and Wieman, but with a condensate containing some hundreds of times more atoms. In an interference experiment he showed that all the atoms really were linked in a single wave of matter. By first separating a condensate into two parts and then causing these to expand into each other, he could observe distinct interference patterns – rather like what happens when two stones are thrown into still water at the same time. The interference pattern would not have formed unless the matter waves were coherent.


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