Few-body physics in ultracold Fermi gases [Elektronische Ressource] / presented by Timo Bastian Ottenstein

Dissertationsubmitted to theCombined Faculties of the Natural Sciences and forMathematicsof the Ruperto-Carola University of Heidelberg, Germanyfor the degree ofDoctor of Natural SciencesPresented byDiplom-Physiker Timo Bastian OttensteinBorn in EberbachOral examination: February 3rd, 2010Few-body physics in ultracold Fermi gasesReferees: Juniorprofessor Dr. Selim JochimProf. Dr. Matthias WeidemüllerAbstractThis thesis reports on experimental studies of few-body physics in ultracold Fermigases. The main part is devoted to the first realisation of an ultracold three-component Fermi gas in thermal equilibrium that consists of atoms in the three6lowest spin states of Li.In first experiments the collisional stability of the gas was investigated in de-pendence of the interparticle interaction. The interaction strength was tuned by anexternal magnetic field employing Feshbach resonances in all three two-body scat-tering channels. At two magnetic field values a resonant enhancement of three-body loss was observed that can be explained by an Efimov-like trimer consistingof one atom in each of the three states which crosses the continuum twice in thestudied magnetic field region. The behaviour of three-body loss rates could beunderstood by taking into account a variation of the lifetime of the trimer with themagnetic field.These experiments were performed with large ensembles of atoms.