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arXiv:cond-mat/0103387 · Physical Review Letters

Bose-Einstein Condensation of Metastable Helium

Franck Pereira dos Santos, Jérémie Léonard, Junmin Wang, C. J. Barrelet, F. Perales, Ernst Maria Rasel, C. S. Unnikrishnan, Michèle Leduc, Claude N. Cohen-Tannoudji

Published Apr 16, 2001• 313 citations
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Abstract

We have observed a Bose-Einstein condensate in a dilute gas of ${}^{4}\mathrm{He}$ in the $^{3}2S_{1}$ metastable state. We find a critical temperature of $(4.7\ifmmode\pm\else\textpm\fi{}0.5)\ensuremath{\mu}\mathrm{K}$ and a typical number of atoms at the threshold of $8\ifmmode\times\else\texttimes\fi{}{10}^{6}$. The maximum number of atoms in our condensate is about $5\ifmmode\times\else\texttimes\fi{}{10}^{5}$. An approximate value for the scattering length $a\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(16\ifmmode\pm\else\textpm\fi{}8)\mathrm{nm}$ is measured. The mean elastic collision rate at threshold is then estimated to be about $2\ifmmode\times\else\texttimes\fi{}{10}^{4}{\mathrm{s}}^{\ensuremath{-}1}$, indicating that we are deeply in the hydrodynamic regime. The typical decay time of the condensate is $2\mathrm{s}$, which places an upper bound on the rate constants for two-body and three-body inelastic collisions.

DOI
10.1103/physrevlett.86.3459

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