Bose-Einstein Condensation (BEC) of weakly interacting atomic gases plays an important role in modern physics. It is related to statistical physics, thermodynamics, quantum mechanics, atomic physics and quantum optics.
Generally BEC is understood as the macroscopic occupation of the gound state of Bosonic atoms. Remarkably this effect is predicted and realized at finite temperatures and without interaction. The phenomenon is entirely derived from the unique quantum statistics of Bosons. While decreasing the temperature of the atomic sample with different cooling stages the de Broglie wavelength of the atoms increases. Finally the mean separation of the atoms and their de Broglie wavelength are of the same order. In this regime the sample has to be described via the Bose-Einstein statistics. Under these conditions stimulated occupation of the ground state occurs. Therefore the ratio of mean separation and de Broglie wavelength is the figure of merit in reaching Bose-Einstein condensation. Because of strong losses due to two and three body processes it is necessary to work with dilute gases at very low temperatures in the nano Kelvin regime.
The BEC project at University of Hannover studies general properties of condensates such as quantized excitations or coherence properties. We are especially interested in the study of ultra cold quantum gases in optical lattices.