An ultracold gas of bosonic 23Na39K ground-state molecules

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dc.identifier.uri Voges, Kai Konrad ger 2020-12-16T07:44:33Z 2020-12-16T07:44:33Z 2020
dc.identifier.citation Voges, Kai Konrad: An ultracold gas of bosonic 23Na39K ground-state molecules. Hannover : Gottfried Wilhelm Leibniz Universität, Diss., 2020, 100, IX S. DOI: ger
dc.description.abstract Ultracold bialkali polar molecules play a leading part at the frontline of quantum physics. They recently attract a lot of attention in the field of ultracold quantum chemistry, quantum many-body physics and quantum simulations. The key for their success is the rich internal level structure with rotational and vibrational degrees of freedom and their large electric dipole moments. Still, only a handful of molecular species are available at ultracold temperatures until now, although it is highly desirable to produce new molecular species to further expand the range of applications. Besides direct laser cooling methods for molecules, the assembly of heteronuclear ground-state molecules from ultracold atomic mixtures is the most promising approach for the creation of polar molecules. It includes the formation of weakly bound Feshbach molecules from the diatomic mixture and the subsequent two-photon stimulated Raman adiabatic passage (STIRAP) transfer to the rovibrational ground state. This creation strategy has been successfully demonstrated for the first time in the pioneering experiments at JILA with ultracold 40K87Rb molecules. Since then, only a few more molecular species from different alkali atoms have been created, namely 6Li23Na, 23Na40K, 23Na87Rb and 87Rb133Cs. In this thesis, I report the successful creation of a new species of ultracold polar ground-state molecules: 23Na39K. Starting from an ultracold mixture of bosonic 23Na and 39K atoms, weakly bound molecules are created. For this purpose, a Feshbach resonance in a high angular momentum scattering channel is chosen, experimentally identified and characterized. Close to this resonance the weakly bound Feshbach molecules are formed using resonant radio frequency radiation. For the two-photon ground-state transfer, a unique, highly specialized two-color laser system is designed and realized. It is used for one- and two-photon spectroscopy to identify the relevant transitions for the ground-state transfer. Based on the obtained data, a local model of the singlet-triplet mixed excited state manifolds is developed, with which the hyperfine structure and the magnetic field dependence is predicted with high accuracy. According to these findings, a suitable pathway to a single hyperfine ground state is chosen considering selection rules and experimental conditions such as laser polarization and beam alignment. To precisely determine the two-photon resonance condition for STIRAP, electromagnetically induced transparency measurements are performed. The ground-state transfer is then performed using STIRAP. The experimental findings regarding the STIRAP are successfully supported theoretically by a model based on a five-level master equation. The pure molecular gas shows evidence for two-body dominated loss mechanisms, such as sticky four-body collisions. The molecule-atom mixture of 23Na39K+39K reveals an unexpectedly low loss rate coefficient although sticky three-body collisions are assumed to occur. This behavior demands further investigations regarding different hyperfine collisional chan-nels and magnetic field regions. eng
dc.language.iso eng ger
dc.publisher Hannover : Institutionelles Repositorium der Leibniz Universität Hannover
dc.rights Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden. ger
dc.subject ultracold molecules eng
dc.subject Bose gases eng
dc.subject Feshbach resonances eng
dc.subject Feshbach molecules eng
dc.subject molecular spectroscopy eng
dc.subject polar molecules eng
dc.subject ultracold collisions eng
dc.subject ultracold atoms eng
dc.subject ultrakalte Moleküle ger
dc.subject Bose-Gase ger
dc.subject Feshbachresonanz ger
dc.subject Feshbachmoleküle ger
dc.subject Molekülspektroskopie ger
dc.subject STIRAP ger
dc.subject polare Moleküle ger
dc.subject ultrakalte Stöße ger
dc.subject ultrakalte Atome ger
dc.subject.ddc 530 | Physik ger
dc.title An ultracold gas of bosonic 23Na39K ground-state molecules eng
dc.type doctoralThesis ger
dc.type Text ger
dc.description.version publishedVersion ger
tib.accessRights frei zug�nglich ger

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