Titel: Creating degenerate two-dimensional Bose gases with tunable interaction strength
Sprache: Englisch
Autor*in: Mozdzen, Alexandra
Erscheinungsdatum: 2024
Tag der mündlichen Prüfung: 2024-09-04
Zusammenfassung: 
This thesis describes the experimental realisation of versatile and highly controllable quantum systems with ultracold quantum gases with the aim to study quantum many-body physics.
In the first part we present the implementation of mesoscopic Fermi-Hubbard-type systems with potassium-40 in a bottom-up approach employing optical tweezers. The experimental setup features an in-vacuo microscope objective with a numerical aperture of 0.75 enabling high-resolution imaging, and allows for tunable interaction strengths via Feshbach resonances as well as for rapid repetition rates due to all-optical cooling schemes. However, reaching quantum degeneracy via Raman-sideband cooling turned out to be very challenging. The achieved 3D ground state fractions of ∼40% is not sufficient to make the study of quantum physics in the Hubbard model feasible.
In the main part of the thesis we discuss how the experimental setup was re-designed and re-built in order to create two-dimensional bosonic bulk systems with potassium-39. The key feature is the rare combination of highly tunable interaction strengths via a variety of intra- as well as interstate Feshbach resonances with the ability to study spin mixtures with high-resolution imaging. We have been able to realise a three-dimensional quasi-pure Bose-Einstein condensate of ∼5 · 10^3 atoms. The sample is then brought into the quasi-two-dimensional regime by first pre-shaping it with a light sheet-like trap and then transferring it into a single layer of a blue-detuned optical lattice. As a result a degenerate two-dimensional Bose gas of ∼3 · 10^3 atoms with a temperature of ∼50nK corresponding to ∼0.2 T_{BKT} is created, where T_{BKT} is the BKT critical temperature. Finally, we discuss how 2D quantum droplets might be realised with the setup.
URL: https://ediss.sub.uni-hamburg.de/handle/ediss/11141
URN: urn:nbn:de:gbv:18-ediss-121029
Dokumenttyp: Dissertation
Betreuer*in: Moritz, Henning
Enthalten in den Sammlungen:Elektronische Dissertationen und Habilitationen

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