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978-3-8439-1595-3, Reihe Physik
From higher bands to higher spins: Ultracold fermions in novel regimes
181 Seiten, Dissertation Universität Hamburg (2013), Softcover, B5
Since the first realization of quantum degenerate gases in dilute atomic vapor, these systems led to a large number of fascinating and sometimes unexpected discoveries. In this thesis, novel approaches for the investigation of two vital research areas are presented: simulation of solid state theories in optical lattices and multicomponent systems composed of particles with high internal spin or mixtures of different species.
In the context of optical lattices, a novel momentum-resolved spectroscopy method for ultracold Fermi gases has been developed. Using this method, the first direct observation of an interaction-induced reduction of tunneling in attractive Bose-Fermi mixtures was achieved. Beyond that, the dynamics of the excitations created in the multiband spectroscopy were found to be in close analogy to photoconductivity in conventional insulating solids, building a new connection between solid state physics and ultracold atoms.
Turning to high-spin Fermi gases, two-particle spin-exchange interactions were observed on individual sites of an optical lattice, including processes with unusually high magnetization exchange. Finally, spin waves in harmonically trapped gases were investigated. The studies especially highlight the tensorial character of these excitations and constitute the first observation of coherent many-body dynamics in high-spin Fermi gases.