When atoms are cooled down to a temperature very close to absolute zero, they tend to "bunch" together in a peculiar way predicted by Bose and Einstein in the 1920s. These "Bose-Einstein condensates" have been produced for the first time in 1995 and are now a tool to investigate the quantum properties of matter. Murray Barrett and Kyle Arnold, in the Microtraps Group of CQT, have recently observed this state of matter in their experiment.
Three absorption images of atom clouds after 20ms of ballistic expansion. On the left the atoms are mostly in the thermal phase, and on the right in condensate phase. The temperatures of the thermal parts from left to right are 200nK, 100nK, and 60nK. The number of atoms from left to right are (180, 100, 60) ×103.