Ultracold quantum gases in three-dimensional optical lattice potentials

摘要: In this thesis I report on experiments that enter a new regime in the many body physics of ultracold atomic gases. A Bose-Einstein condensate is loaded into three-dimensional optical lattice potential formed by standing wave laser light field. this novel quantum system we have been able to both realize quantum phase transition from superfluid Mott insulator, and to observe the collapse revival macroscopic matter wave field. Quantum phase transitions are driven fluctuations and occur, even at zero temperature, as relative strength two competing energy terms in underlying Hamiltonian varied across critical value. first part work report on observation such a Bose-Einstein condensate with repulsive interactions, held a three-dimensional lattice potential. superfluid ground state, each atom spread-out over entire lattice, whereas insulating exact numbers atoms are localized individual sites. We observed reversible transition between those states detected gap the excitation spectrum insulator. A Bose-Einstein usually described macroscopic matter However, quantized field underlies a "classical" condensate. The striking behavior due field quantization nonlinear interactions is the focus second work. The field of undergo series of collapses revivals time evolves. Furthermore, show that the collisions pairs lead fully coherent collisional shift corresponding many-particle which crucial cornerstone proposed novel computation schemes neutral atoms. With these with ultracold strongly correlated regime, interactions dominate many-body system it can no longer be usual theories for weakly interacting Bose This novel quantum system offers unique possibility experimentally address fundamental questions modern solid state physics, atomic physics, optics, information.