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Helium work is really hopping in France

Leduc/Cohen-Tannoudji graph

[Historical report created from GSU BEC Homepage:]

"A Bose Einstein condensate (BEC) of helium atoms in the metastable triplet state has been observed at ENS in Paris during the evening of 20 February 2001 at Laboratoire Kastler Brossel. The critical temperature is about 4.5 µK. At the transition threshold the cloud contains about 8 million atoms. The condensate is produced in a Ioffe-Pritchard magnetic trap, loaded from a magneto-optical trap containing about one billion atoms at 1 mK. The BEC results of an evaporation ramp lasting 15 s.

The detection is optical, based on the absorption of a probe laser beam at 1.08 microns measured on a CCD camera.

The figure above shows images of a condensate (of about 400000 atoms) for an increasing expansion time after the trap has been switched off. The inversion of the ellipticity resulting from the mean field in the condensate is a clear evidence for the existence of a BEC.

The team is composed of:
PhD students: Franck Pereira Dos Santos, Jérémie Léonard
Permanent members: Michèle Leduc, Claude Cohen-Tannoudji
Postdocs and visitors: Carl Barrelet, Francisco Perales, Ernst Rasel, Junmin Wang

Further information are available on our WebSite."