From the production of Bose-Einstein Condensates in 1995, to the demonstration of superfluidity in a strongly interacting mixture of degenerate Fermi gases, the research on ultracold atomic gases has progressed to increasingly sophisticated and complex systems. This interest is driven by the desire to understand strongly interacting and strongly correlated systems, with applications in solid-state physics (high temperature superfluidity), nuclear physics, astrophysics (neutron stars), quantum computing, and nanotechnologies.
Within our research we control these systems via external magnetic (Feshbach resonances) and laser fields (photoassociation, optical lattices). Feshbach resonances have enabled the investigation of molecular BEC, and the study of the BEC-BCS crossover. Control of optical lattices has enabled the observation of the superfluid to Mott-insulator phase transition. Today, the combination of these methods paves the way towards the investigation of ultracold molecular gases.
By interfering laser beams it is possible to form a potential for ultracold atoms that is strikingly similar to the crystalline structure of solid state systems. This allows for the investigation of condensed matter phenomena in a very pure and adjustable environment. Thus atoms in an optical lattice can provide a "simulator" for solid state many-body systems and may allow us to answer unsolved questions of the field.
Within this project heteronuclear molecular quantum gases are investigated with the aim of controlling reactive collisional processes. In particular mixtures of 41K and 39K with 87Rb allow for the creation of bosonic molecular quantum gases by using so-called Feshbach resonances to associate the molecules.
We currently constructing a new experiment which will combine high resolution detection and manipulation in optical lattices with active control of the quantum mechanical evolution using quantum non-demolition (QND) measurements of ultracold atoms by applying feedback onto the system.
In a collaboration between the Institut für Quantenoptik (IQ) and the Institut for Fysik og Astronomi (IFA) our group contributes to the investigation of mixed quantum gases and their dynamics. The experiment is located at the Institut für Quantenoptik (IQ), Leibniz Universität Hannover.