Bulletin of the American Physical Society
40th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 54, Number 7
Tuesday–Saturday, May 19–23, 2009; Charlottesville, Virginia
Session B1: Magnetism in Ultracold Gases and Spinor Gases |
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Chair: Daniel Goldbaum, University of Arizona Room: Chemistry Building 402 |
Wednesday, May 20, 2009 10:30AM - 11:00AM |
B1.00001: Repulsively and Attractively Interacting Fermi-Mixtures in Optical Lattices Invited Speaker: Ultracold fermionic quantum gases in optical lattices represent a unique model scheme which in principle can be used to simulate complex many-body systems, for example high-Tc superconductors. Similarly to solid state physics, our system is described by the Fermi-Hubbard Hamiltonian with the advantage that all relevant parameters can be controlled with high accuracy. A famous prediction of the Hubbard Hamiltonian is the Mott-insulator, where a metal with half-filled conduction band turns insulating due to interactions. Experimentally, we prepare a fermionic Mott-insulator with an ultracold repulsively interacting spin mixture of $^{40}$K atoms in a blue detuned optical lattice. By measuring the insitu cloud size and its response to an external force - the enclosure of a red detuned optical dipole trap - as well as the number of doubly occupied sites, the insulating and metallic behaviour can be distinguished; and the Mott-insulating regions can be identified. The interactions between the atoms can conveniently be tuned with the help of a magnetic Feshbach resonance. However, the attractive side of the resonance, i.e. the attractive Hubbard-Hamiltonian, contains surprising effects as well. On tuning the interactions from the repulsive to the attractive side, we find a shrinking followed by an anomalous expansion of the atomic cloud. This unexpected expansion is related to the formation of bound pairs and can be understood with a straightforward entropy argument. This work was done together with U.Schneider, S. Will, Th. Best, S. Braun, I. Bloch and with theoretical support from T.A.Costi, R.W. Helmes, D. Rasch, A.Rosch, B. Paredes, M. Moreno-Cardoner, T. Kitagawa, E.Demler. [Preview Abstract] |
Wednesday, May 20, 2009 11:00AM - 11:30AM |
B1.00002: Magnetism of ultracold atoms in optical lattices Invited Speaker: In this talk I will review recent progress in the study of magnetic superexchange interactions of ultracold atoms in optical lattices. [Preview Abstract] |
Wednesday, May 20, 2009 11:30AM - 12:00PM |
B1.00003: Supersolidity in a quantum degenerate dipolar spinor gas Invited Speaker: I will describe studies on the magnetic and superfluid order of quantum degenerate $F=1$ $^{87}$Rb spinor gases. In these magnetic quantum fluids, we observe the spontaneous emergence of a self-organized phase exhibiting a crystalline ordering of magnetic domains. We ascribe this spatial organization to the competition between the short-range ferromagnetic interaction and the long-range magnetic dipolar interaction. Further, via Bragg spectroscopy of this dipolar quantum fluid, we confirm the presence of long-range phase coherence (characteristic of a superfluid) co-existing with the crystalline magnetic order. Together, these results provide strong experimental evidence for the realization of the supersolid phase of matter. [Preview Abstract] |
Wednesday, May 20, 2009 12:00PM - 12:30PM |
B1.00004: Dynamics and generation of fractionalized vortices in spinor BECs Invited Speaker: Quantum number fractionalization is one of the most fascinating concepts studied in modern many-body physics and topological field theories. In this talk, I am going to first discuss the basic concept of vortex fractionalization in spinor BECs and peculiar interactions between these fractionalized excitations. The second half of my talk will be focused on dynamics, and possibilities of generating and probing these exotic excitations in BECs of cold atoms. [Preview Abstract] |
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