16
September 2004
Extending the trap
Magnetic trapping and cold collisions are key to the production of quantum degenerate atomic and molecular gases such as Bose-Einstein condensates, the ultracold 'superatom' state of matter. A condensate is produced when atoms — often rubidium — are trapped magnetically in a vacuum and cooled to few billionths of a degree above absolute zero. Magnetic trapping requires a certain alignment of atomic spin with respect to the trap field. This alignment can be destroyed by atomic collisions, limiting the technique to a few atomic species — mainly spherically symmetric alkali metal atoms — which can collide without disrupting spin orientation. As part of a project to create quantum degenerate gases in a broader class of non-spherically symmetric atoms throughout the periodic table, Hancox et al. looked at a subset of the rare earths, including neodymium and dysprosium. Their outer filled electronic shells effectively cause them to behave like spherically symmetric atoms, suppressing spin-disrupting collisions. With these atoms as starting points, low-temperature studies of many new systems should become possible.
Magnetic trapping of rare-earth atoms at millikelvin
temperatures
CINDY I. HANCOX, S. CHARLES DORET, MATTHEW T. HUMMON,
LINJIAO LUO & JOHN M. DOYLE
Nature 431, 281–284 (2004); doi:10.1038/nature02938
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