Dresden 2011 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 57: Poster 3: Quantengase, Ultrakalte Atome, Ultrakalte Moleküle, Materiewellen Optik, Präzisionsmessungen, Metrologie
Q 57.29: Poster
Donnerstag, 17. März 2011, 16:30–19:30, P1
Magnetic phases of spinor quantum gases in hexagonal optical lattices — •Eva-Maria Richter1, Dirk-Sören Lühmann2, and Daniela Pfannkuche1 — 1I. Institut für Theoretische Physik, Universität Hamburg, Germany — 2Institut für Laser-Physik, Universität Hamburg, Germany
Ultracold quantum gases in optical lattices have been established as a continuously growing field of research with various applications in different areas of science. While cubic lattices are theoretically and experimentally investigated in the majority of cases so far, our focus rests on spinor bosons in hexagonal lattices. By employing a triangular optical lattice with defined polarized laser beams, a hexagonal 'magnetic' optical lattice is created. Bosonic atoms in different spin quantum states are subject to different optical potentials, which depend on their internal state. Thus, the hexagonal optical lattice consists of two sublattices A and B, induced by the polarization which is mapped to an effectiv site dependent magnetic field. This leads to a spin dependent Zeeman shift beetween the two sublattices. Starting from the Bose-Hubbard-Hamiltonian and within the framework of exact diagonalization for finite systems with periodic boundary conditions we investigate the different quantum phases depending on various lattice parameters and different particle numbers. We discriminate different phases by their corresponding pair-correlation functions. Phases with next-neighbour pairing are observed as well as antiferromagnetic ordering. We compare our numerical results with those of a meanfield approximation and with experiments.