Lu, Zhenkai (2016): Towards many body physics with ultracold NaK molecules. Dissertation, LMU München: Fakultät für Physik
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### Abstract

This thesis reports on the construction of a novel experimental apparatus to create an ultracold sample of chemical stable $^{23}\rm{Na}^{40}\rm{K}$ polar molecules at their absolute ground states. The long range nature of the dipolar interactions between the ground state molecules, is expected to facilitate to observe new quantum many-body states and to simulate prototypical lattice spin models for exploring quantum magnetism and high $T_c$ superconductivity. The experimental procedures are presented in this thesis including: trapping and cooling $^{23}\rm{Na}$ and $^{40}\rm{K}$ atoms to quantum degeneracy, associating weakly bound state molecules with Feshbach resonances, and transferring the Feshbach molecules to the rovibrational ground states via stimulated Raman adiabatic passage. As a result, successful transfer has been demonstrated in our experiment with a single-path transfer efficiency $\simeq 60\%$ via a hyperfine non-resolved intermediate state $\vert d^{3}\Pi, \nu=5, J=1, \Omega=1 \rangle$. In addition, a perturbative theoretical study on the Fermi liquid properties of a single-component weakly-interacting two dimensional dipolar fermions with dipole moments $d$ oriented perpendicularly to the plane of their translational motion is presented in the thesis. When the dipole moments are tilted with respect to the translational plane, the effect of anisotropic interaction appears, and collective excitations in the collisionless regime are studied in this configuration. Furthermore, stable dilute supersolid states with two-dimensional bosonic dipoles are predicted to exist with an additional three-body repulsive contact interaction. These novel quantum effects should be accessible experimentally once the $\rm{Na}\rm{K}$ ground state molecules reach quantum degeneracy by further evaporative cooling.

### Abstract

Deutsche Übersetzung des Titels: Vielteilchenphysik mit ultrakalten NaK Molekülen