Issue Date: July 14, 2008
Two teams of researchers have demonstrated that laser methods can be used to cool molecules to near absolute zero. Ensembles of molecules with nearly zero energy provide opportunities to explore quantum phenomena that cannot be observed in energetic systems. Ultracold molecules may also be useful for high-resolution spectroscopy and quantum computing. Laser-based methods for stripping energy from atoms have been used for 20 years to produce nearly motionless collections of atoms in a state of matter known as a Bose-Einstein condensate. Efforts to apply those types of methods to molecules, however, have generally yielded molecules with little translational energy but considerable rotational and vibrational energy. Scientists have now figured out ways to reduce much of the internal molecular energy. At the University of Paris-Sud, in France, Pierre Pillet and colleagues have devised a laser method for downshifting cold Cs2 molecules that occupy a distribution of vibrational states into the ground vibrational state (Science 2008, 321, 232). And Johann G. Danzl at the University of Innsbruck, in Austria, and colleagues have shown that a different laser scheme can reduce Cs2's rotational energy (Science, DOI: 10.1126/science.1159909).
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