Bose-Einstein condensation of an atomic gas

It is now possible to produce in the laboratory ultra-cold gases whose properties are very far from intuition. A large fraction of the atoms occupy the same quantum state, confirming thus a prediction made by Einstein 75 years ago. The discovery of these atomic condensates has allowed for a precise check of theoretical models initially developed to account for the superfluidity of cold liquid Helium. It opens the way to coherent atomic sources, which are the equivalent, for matter waves, of the maser and laser sources for electromagnetic waves.