LiNaK: Multi-Species Apparatus for the Study of Ultracold Quantum Degenerate Mixtures

This thesis describes the construction of a versatile apparatus to study ultracold quantum mixtures capable of simultaneously cooling fermionic Li and K, as well as the bosonic K. The main features of the experimental setup are presented, in particular the addition of a new species Na, which has enabled the study of the Bose-Fermi mixture Na-K. Three main experimental benchmarks are outlined: first, the production of a Bose-Einstein Condensate of K is discussed and an evaluation of its properties as a coolant are analysed. Secondly, the creation of triply degenerate Bose-Fermi-Fermi of K-K-Li gas is presented. Simultaneous observation of Pauli Pressure and Bose Condensation in the triply degenerate gas is reported. In addition, interspecies Feshbach resonances between K-K and Li-K are observed, opening the way to the study of a strongly interacting isotopic Bose-Fermi mixture of K-K, which have similar mass. Thirdly, the creation of a quantum degenerate Bose-Fermi mixture of Na-K is discussed and over thirty Feshbach resonances are identified. Finally, a degenerate Na-K Bose-Fermi mixture opens the way to creating fermionic NaK ground state molecules, which are known to be chemically stable and have a larger permanent electric dipole than KRb. This thesis concludes with a review of the molecular properties of NaK and explores the possibilities of bringing Feshbach molecules of NaK into the singlet rovibrational ground state. Thesis Supervisor: Prof. Martin W. Zwierlein Title: Associate Professor