Drewes, Jan Henning: Thermodynamics and correlations of ultracold fermions in a two-dimensional optical lattice. - Bonn, 2022. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5-66567
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5-66567,
author = {{Jan Henning Drewes}},
title = {Thermodynamics and correlations of ultracold fermions in a two-dimensional optical lattice},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2022,
month = may,

note = {This thesis reports on experiments with ultracold fermionic 40K atoms in an optical lattice realising a quantum simulation of the two-dimensional Hubbard model. A central aspect of the experiments presented here is the combination of radio frequency spectroscopy techniques and a high resolution imaging setup. Thereby, both the in-situ density and spin distributions can be studied in a spatially resolved way.
In a first experiment, the in-situ density distribution has been investigated. Due to the high resolution of the imaging system, phases coexisting in the inhomogeneous trapping potential have been distinguished. Furthermore, the precise characterisation of the external confinement allows to determine the density equation of state, which fully characterises the thermodynamic properties of the many-body system in the investigated range of temperatures. As a hallmark of the repulsive Hubbard model, the crossover from a metal to a Mott-insulator has been observed.
Furthermore, the precise determination of the equation of states allows us to apply the fluctuation dissipation theorem, in order to infer the suppression of non-local density fluctuations in the repulsive Hubbard model from the compressibility and the on-site occupation.
Finally, a study of the spin degree of freedom is presented. This experiment relies on a novel spin sensitive detection technique, which has been developed during this thesis. Through a correlation analysis of the spatially resolved spin distribution, we have been investigating the influence of doping, interactions and temperature on the uniform spin structure factor. For strongly repulsive interactions and low temperatures, the data show the onset of antiferromagnetic correlations in the Mott-Insulator, which is a key step towards investigating the low temperature phase diagram of the two dimensional Hubbard model.},

url = {https://hdl.handle.net/20.500.11811/9814}

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