LiNaK : multi-species apparatus for the study of ultracold quantum degenerate mixtures

Abstract

This thesis describes the construction of a versatile apparatus to study ultracold quantum mixtures capable of simultaneously cooling fermionic ⁶Li and ⁴⁰K, as well as the bosonic ⁴¹K. The main features of the experimental setup are presented, in particular the addition of a new species ²³Na, which has enabled the study of the Bose-Fermi mixture ²³Na-⁴⁰K. Three main experimental benchmarks are outlined: first, the production of a Bose-Einstein Condensate of ⁴¹K is discussed and an evaluation of its properties as a coolant are analysed. Secondly, the creation of a triply degenerate Bose-Fermi-Fermi gas of ⁴¹K-⁴⁰K-⁶Li is presented. Simultaneous observation of Pauli Pressure and Bose Condensation in the triply degenerate gas is reported. In addition, interspecies Feshbach resonances between ⁴¹K-⁴⁰K and ⁶Li-⁴¹K are observed, opening the way to the study of a strongly interacting isotopic Bose-Fermi mixture of ⁴¹K-⁴⁰K, which have similar mass. Thirdly, the creation of a quantum degenerate Bose-Fermi mixture of ²³Na-⁴⁰K is discussed and over thirty Feshbach resonances are identified. Finally, a degenerate ²³Na-⁴⁰K 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.