Abstract

We produce a novel Bose-Einstein condensate composed of ³⁹K atoms. Condensation of this species was so far prevented by a naturally small and negative scattering length. We now use a combination of sympathetic cooling with ⁸⁷Rb and direct evaporation, exploiting the magnetic tuning of both inter- and intra-species interactions at Feshbach resonances. We explore tunability of the self-interactions by studying the expansion and the stability of the condensate, in the vicinity of one very broad Feshbach resonance. We find that a ³⁹K condensate is very interesting for experiments requiring a weakly interacting Bose gas, such as atom interferometry experiments. Here a Bose-Einstein condensate with interactions tunable to zero would provide the ideal source for high precision, high-resolution inertial sensing, combining the maximal brightness with the absence of collisional decoherence. We will report on the properties of the ³⁹K Bose-Einstein condensates, and on ongoing experiments on atom interferometry.

© 2007 IEEE