Molecules get a Big Chill

Stopping big molecules cold in their tracks just got a little easier, thanks to a new trick that nudges them closer to ultracold temperatures. Physicists have previously chilled atoms and pairs of atoms to fractions of a degree above absolute zero — a lab feat that has revealed new physics and chemistry of matter. Now, Germanscientists have started to do the same for molecules made of manyatoms. The work is “a real important step forward towards realizing cold andultracold molecular samples,” says Guido Pupillo, a physicist withthe French National Center for Scientific Research and the University of Strasbourg. Supercold temperatures can bring superhot discoveries. Early studies, for instance, showed how ultracold atoms can lose their individual identities and behave instead as a single quantum entity.Later work allowed scientists to manipulate how two ultracold atoms join together. But the laser cooling techniques used so far don’t work well for bigger molecules with complex energy levels. A team led by Martin Zeppenfeld of the Max Planck Institute for Quantum Optics in Garching, Germany, decided to explore a new method, called optoelectrical cooling, that circumvents the energy-level problem. “Our method eliminates the primary hurdle in producing ultracold polyatomic molecules,” the scientists wrote online July 31 at arXiv.org. Zeppenfeld declined to discuss the work until it is published in a peer-reviewed journal.