The Multi specIes eXperiment - MIX

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 ground state of a system 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 an atomic sample with multiple cooling mechanisms, the de Broglie wavelength of the individual 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 by Bose-Einstein statistics and eventually a macroscopic occupation of the ground state occurs. Therefore the ratio of mean separation and de Broglie wavelength is the figure of merit for reaching Bose-Einstein condensation.

The BEC project at Institut für Quantenoptik was the first experiment to reach quantum degeneracy in northern Germany. It was strted 1996, funded by the Sonderforschungsbereich SFB407 and produced the first BECs in 1998. From then on many general properties of condensates were studied, such as quantized exitations (solitons) and phase fluctuations. In recent years the implementation of a 1D optical lattice allowed for the investigation of localization and transport phenomena in analogy with solid state physics. In particular the controlled addition of disordered potentials to the system led to interesting experiments on Anderson localization an dephased bloch oscillations.

Since 2008 a new experimental setup has been realized, supported by QUEST (Centre for Quantum Engineering and Space-Time Research). The vacuum system offers outstanding optical access which will enable the implementation of complex optical lattices. A novel hybrid trap allows for the very stable production of large BEC. (In the picture you see an atom laser – a beam coupled out of this trap). Beyond that all potassium isotopes ³⁹K, ⁴⁰K and ⁴¹K can be used in addition to rubidium.

Thus the experiment is called  MIX – Multi specIes eXperiment. Further information about the experimental setup can be found here, our current research projects are presended here.