Exotic quantum matter

   The Exotic Quantum Matter Group experimentally investigates strongly correlated quantum matter at the boundary of few-body and many-body physics using long-range interacting quantum gases in confined geometries.

By laser trapping and cooling atomic gases close to absolute zero temperature, it is possible to create new phases of matter in which the quantum statistics of the particles (i.e. bosonic vs. fermionic) and their interactions determine the behaviour of the system. These quantum gases offer an ideal testing-ground to investigate exotic many-body quantum phenomena with full control over the macroscopic and microscopic degrees of freedom. Until recently, cold atom experiments have dealt with regimes in which interactions between particles had either a point-like character or played a relatively minor role. Now a new frontier is emerging, exciting from both theoretical and experimental points of view, in which interactions can be controlled in completely new ways giving rise to new and more complex many-body effects.

We are now starting to address some of the big questions, such as, to what extent finite range interactions modify the properties of quantum fluids and how does superfluidity and magnetism arise in diverse settings. Future studies of these systems will reach far beyond the current understanding of relatively simple quantum systems and will provide new insights into emergent phenomena in collective and strongly-correlated regimes. Ultimately, these principles could be applied to create novel designer materials or quantum devices which will exploit quantum properties in new ways.

Envisioned experimental setup. Ultracold atoms (purple spheres) are confined in an optical potential which forms a lattice of 1D tubes (yellow cylinders). Off-resonant coupling of the atoms to highly excited Rydberg states with an electric dipole moment introduces interactions between atoms which extend over several micrometers. By controlling the orientation of the dipoles using an external electric field it is possible to independently control both intra- and inter-tube interactions.

To help answer these questions a new experimental apparatus is being developed in Heidelberg. It involves confining quantum degenerate gases of Potassium-40 atoms (fermions) in optical traps and lattices, and it will combine single-atom sensitive imaging of atoms with coherent optical coupling to highly excited atomic states (“Rydberg dressing”), as a means to control the strength and shape of atomic interactions in totally new ways.

Our experiments will focus on the new phases of matter which arise in spatially separated traps coupled by long-range interactions. By direct imaging of density-density correlations, our results will shed new light on quantum effects in complex many-body phenomena, elucidating the effects of quantum statistics and correlations in 1D quantum gases, the roles of dynamics and quantum entanglement near quantum phase transitions, and the emergence of macroscopic effects such as superfluidity and magnetism in quantum systems.

For more information on our research see our publications page.