%0 Generic
%A Repp, Marc
%D 2013
%F heidok:14993
%R 10.11588/heidok.00014993
%T Interspecies Feshbach Resonances in an Ultracold, Optically Trapped Bose-Fermi Mixture of Cesium and Lithium
%U https://archiv.ub.uni-heidelberg.de/volltextserver/14993/
%X This thesis reports on the tunability of interactions in ultracold Bose-Fermi mixtures of Cesium and Lithium. The   first realization of an optically trapped  6Li -133Cs mixture enabled to perform trap loss spectroscopy measurements to identify  magnetic Feshbach resonances. A total of 19 interspecies Feshbach resonances, all in the magnetic field range between 650 G and 950 G, were observed for the two energetically lowest spin states of each species. Two 5 G broad and especially two 60 G broad s-wave resonances give perspectives to produce a dipolar quantum gas of LiCs ground state molecules as well as to study the Efimov effect in highly mass imbalanced systems. In addition, a unique relative tunability of intra- and interspecies  scattering lengths was found which makes the 6Li -133Cs system also well suited for the investigation of polarons. Evaporative cooling was performed on optically trapped samples which contained only one of the species. In this way, Bose-Einstein condensates of 6Li molecules as well as 133Cs samples at a phase-space density of p = 4 · 10^2 were prepared. All experiments were performed in a new apparatus, which has been designed and set up during this thesis.