Spin segregation puzzles physicists

From physicsworld.com: headline news:

Physicists in the US are the first to segregate a Fermi gas of ultracold atoms according to their spin — with "spin-up" and "spin-down" atoms moving to opposite sides of the optical trap in which they were contained. John Thomas and colleagues at Duke University found that about 60% of the lithium-6 atoms became segregated and that the spin-up and spin-down atoms remained apart for several seconds. However, they are puzzled as to why the segregation lasts much longer, and is more intense, than predicted by theory (Phys. Rev. Lett. 101 150401 ). Spin segregation is interesting for physicists because it plays an important role in "spintronics", where it is used to create currents of spin-polarized electrons. As lithium-6 atoms and electrons are both fermions — that is, particles with half-integer spin — the new system could therefore be used as a "quantum simulator" of spintronic devices. Although Eric Cornell and colleagues at the University of Colorado have previously been able to segregate an ultracold atomic gas of bosons (rubidium atoms with integer spin) in terms of spin, such a system has not been useful for simulating interactions between electrons in solids because fermions and bosons behave so differently.

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