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 dipole trap). Feshbach resonances have enabled the tuning of interactions between atoms, giving rise to a broad range of research areas from few-body Efimov physics towards strongly interacting many-body quantum systems. By carefully preparing our atomic samples, we have reached unprecedented control in the final number of atoms. This opens up the way to investigate fluctuations in quantum systems.
Fluctuations are a key property of both classical and quantum systems. While the fluctuations are well understood for many quantum systems at zero temperature, the case of an interacting quantum system at finite temperature still poses numerous challenges. Despite intense theoretical investigations of atom number fluctuations in Bose-Einstein condensates (BECs), their amplitude in experimentally relevant interacting systems is still poorly understood. Our experiments are based on a stabilization technique, which allows for the preparation of ultracold thermal clouds at the shot noise level, which as lead to the first observation of these fluctuations.
Mobile impurity particles interacting with a bosonic quantum environment play a central role in our understanding of nature and are fundamental for several important technologies such as organic electronics. Ultracold atomic gases provide a clean and highly controllable platform to study impurity physics across interaction regimes, enabling precise tests of many-body theories. We utilize multicomponent ultracold atomic gases to primarily investigate long-lived impurity atoms in an atomic Bose-Einstein condensate.
We are also interested in few-body Efimov physics, quantum engine realizations as well as systems with beyond mean-field interactions.
