TY  - GEN
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/19214/
Y1  - 2015///
A1  - Ulmanis, Juris
AV  - public
ID  - heidok19214
TI  - Universality and non-universality in the heteronuclear Efimov scenario with large mass imbalance
N2  - This thesis investigates universal and non-universal aspects of few-body physics in a mass-imbalanced mixture of ultracold  bosonic $^{133}$Cs and fermionic $^6$Li atoms. For this purpose an experimental apparatus for the creation of quantum degenerate gases has been constructed. Using radio-frequency association of weakly-bound LiCs molecules and additional atom-loss spectroscopy we determine the two-body interaction properties between Li and Cs atoms at low collision energies. The analysis with a coupled-channels calculation yields precise singlet and triplet electronic ground state molecular potential curves, from which scattering lengths and positions of Fano-Feshbach resonances are extracted. These results represent almost a tenfold improvement over the previous determination, and are used to study few-body recombination processes  and, for the first time, their dependence on the interaction strength between the heavy atoms close to two broad scattering resonances at various temperatures. Measurements of three-body loss rates reveal two series of three and two consecutive LiCs$_2$ Efimov resonances that demonstrate the universal scaling factor 4.9 between the first and second excited state resonances. The ground state resonance deviates from the discrete scaling law. By the use of hyperspherical formalism with either pairwise zero-range or Lennard-Jones model potentials we identify the van der Waals interaction between Cs atoms as a significant source of these modifications. 
ER  -