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BEC over troubled water?

On Tuesday April 25, 2006 we observed our first Bose-Einstein condensate (BEC) on a chip in the "CELSIUS" experiment. The signature was the sudden appearance of an anisotropically expanding cloud when smoothly increasing the phase-space density through forced evaporative cooling.

Since then, we have optimized our evaporation trajectory and made various other improvements. Now we routinely reach Bose-Einstein condensation at at a temperature of around Tc = 1.5 µK, with 105 atoms (87Rb), in a cylindrically symmetric harmonic trap. Further evaporative cooling results in a nearly pure condensate of about twenty thousand atoms.

The images below (taken in August 2006) show a cloud just above the critical temperate (left), a partially condensed cloud (middle), and a nearly pure condensate (right) respectively.

van Druten graph