Laser-cooled Nobel prize
Nov 7, 1997
Claude Cohen-Tannoudji, Steve Chu, and Bill Phillips have won the 1997 Nobel prize of Physics.
Winning the Nobel prize for physics is like being hit by a tornado, according to one of this year's laureates. "I just wish it would stop so that I could go back to work, " says Claude Cohen-Tannoudji of the Collège de France and the Ecole Normale Supérieure in Paris. He shares the 1997 prize with Steve Chu of Stanford University in California and Bill Phillips of the National Institute of Standards and Technology in Gaithersburg, Maryland, for developing techniques to cool and trap atoms at extremely low temperatures using lasers.
If a laser beam is tuned to just below an atomic transition frequency, an atom moving in the opposite direction to the beam will absorb photons due to the Doppler effect, whereas an atom moving in the same direction will not. When an atom absorbs a photon it also absorbs the photon's momentum, so atoms moving towards the laser are slowed down.
By arranging a pair of lasers to face one another, it is possible to trap and cool atoms to temperatures of a few microkelvin. This was first done by Phillips and colleagues. Chu and co-workers, then at Bell Labs, extended the technique into three dimensions. Cohen-Tannoudji later showed how atoms could be cooled to even lower temperatures.
The Nobel prize for chemistry also had physics connections. Jens Skou, a professor of biophysics at Aarhus University in Denmark, shared the chemistry prize for the first discovery of an ion-transporting enzyme. John Walker of the Laboratory of Molecular Biology in Cambridge, UK, who shared the chemistry prize with Skou and Paul Boyer of the University of California at Los Angeles, used synchrotron radiation to determine the structure of the enzyme adenosine triphosphate (ATP).