Ultracold atom

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Ultracold atoms are atoms that are maintained at temperatures close to 0 kelvin (absolute zero), typically below temperatures of some tenths of microkelvins (µK). At these temperatures the atom's quantum-mechanical properties become important. To reach such low temperatures, a combination of several techniques has to be used. First atoms are usually trapped and pre-cooled via laser cooling in a magneto-optical trap. To reach the lowest possible temperature, further cooling is performed using evaporative cooling in a magnetic or optical trap.

If sufficiently low temperatures are reached the atoms form a new state of matter that is governed by quantum mechanics. For bosonic atoms this state is a Bose–Einstein condensate, for fermionic atoms it is a degenerate Fermi gas.

Experiments with ultracold atoms are important for understanding quantum phase transition and studying Bose–Einstein condensation (BEC), bosonic superfluidity, quantum magnetism, many-body spin dynamics, Efimov states, Bardeen-Cooper-Schrieffer (BCS) superfluidity and the BEC-BCS crossover.[1]

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  1. ^ Madison, K. W.; Wang, Y. Q.; Rey, A. M. et al., eds. (2013). Annual Review of Cold Atoms and Molecules. World Scientific. ISBN 978-981-4440-39-4.