Last year, physicists at Innsbruck in Austria reported the strongest evidence to date for superfluidity in an ultracold gas of fermionic atoms when they observed the "pairing gap" in an ultracold Fermi gas for the first time. The observation of a similar gap in low-temperature superconductors in the late 1950s was a major milestone in the quest to understand these materials. The new results, which agree with theoretical calculations by a second group in Finland, could help us understand more about high-temperature superconductivity and systems as diverse and exotic as neutron stars, atomic nuclei and quark-gluon plasmas. The gap was observed in experiments on "fermionic condensates", a new state of matter that was reported for the first time by a group in the US in January 2004.
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