Bose-Einstein condensates a new form of quantum matter

We review the recent achievements in observing Bose-Einstein condensation (BEC) in magnetically-trapped gases, and summarize our own studies of BEC in sodium. Thermal sodium atoms were optically trapped and cooled and then transferred to a cloverleaf magnetic trap. Radio-frequency induced evaporation increased the phase-space density by six orders of magnitude and condensates with up to ten million atoms were observed. Basic properties of the condensate such as condensate fraction and mean-field energy were found to be in agreement with theory. “Dark-ground” imaging has been used to observe the condensate directly and nondestructively. We have also investigated the low frequency oscillation modes of a condensate, and taken the first steps towards an “atom laser” by demonstrating an rf output coupler for a Bose condensate.