The above figure demonstrates two different atoms interacting in the presence of
their respective Fermi seas. Fermi surfaces are different since the number of atoms in different components was unequal. This kind of setup is studied when the classic Cooper problem is solved in a lattice. Some other topics with which NORDITA researchers have been active include the following.
- Bose-Einstein condensation: When a gas composed of bosons is cooled to very low temperatures, large fraction of atoms can eventually move a same quantum state. This phenomena is called Bose-Einstein condensation. Researchers in Nordita are active in the field of Bose-Einstein condensation and have studied different aspects condensates. For example, superfluid properties, quantized vortices, dynamics, multi-component condensates, condensate fragmentation... a recent article on vortices in bosonic systems)
- Ultracold fermions: When fermions are cooled they cannot drop to a single quantum state like bosons due to Pauli exclusion principle. However, if the fermions interact they can nevertheless start forming Cooper pairs and form a superfluid. As interaction are changed it is possible to realize BCS-BEC crossover from large Cooper pairs to small molecules which can Bose condense. Researchers in Nordita are actively involved in studying many body physics of ultracold fermions.
- Physics in optical lattices: Optical lattices are external potentials created with interfering laser beams that atoms experience. They provide a very versatile tool to study quantum many body physics. Researchers in Nordita are studying physics in optical lattices, both for fermions as well as for bosons.