Bulletin of the American Physical Society
2008 APS March Meeting
Volume 53, Number 2
Monday–Friday, March 10–14, 2008; New Orleans, Louisiana
Session P7: Optical Lattices |
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Sponsoring Units: DAMOP Chair: Charles Clark, National Institute of Standards and Technology, Gaithersburg Room: Morial Convention Center RO5 |
Wednesday, March 12, 2008 8:00AM - 8:36AM |
P7.00001: Repulsively bound atom pairs in an optical lattice. Invited Speaker: Three dimensional optical lattices represent an interesting environment for fundamental research with ultracold atoms. We have observed a novel kind of stable bound state of two atoms which is based on repulsion rather than attraction between the particles [1]. We will explain how these lattice-induced repulsively bound atom pairs come about and discuss their interesting properties. Ensembles of repulsively bound pairs are described by a Bose-Hubbard model and can be used to study strongly correlated condensed matter physics. [1] K. Winkler et al., Nature 441, 853 (2006).~ [Preview Abstract] |
Wednesday, March 12, 2008 8:36AM - 9:12AM |
P7.00002: Critical velocity for superfluid flow across the BEC-BCS crossover Invited Speaker: Critical velocities have been observed in an ultracold superfluid Fermi gas throughout the BEC-BCS crossover. A pronounced peak of the critical velocity at unitarity demonstrates that superfluidity is most robust for resonant atomic interactions. Critical velocities were determined from the abrupt onset of dissipation when the velocity of a moving one-dimensional optical lattice was varied. The dependence of the critical velocity on lattice depth and on the inhomogeneous density profile was studied. [Preview Abstract] |
Wednesday, March 12, 2008 9:12AM - 9:48AM |
P7.00003: Towards Quantum Magnetism with Ultracold Quantum Gases in Optical Lattices Invited Speaker: Quantum mechanical superexchange interactions form the basis of quantum magnetism in strongly correlated electronic media and are believed to play a major role in high-Tc superconducting materials. We report on the first direct measurement of such superexchange interactions with ultracold atoms in optical lattices. After preparing a spin-mixture of ultracold atoms with the help of optical superlattices in an antiferromagnetically ordered state, we are able to observe a coherent superexchange mediated spin dynamics down to coupling energies as low as 5 Hz. Furthermore, it is shown how these superexchange interactions can be fully controlled in magnitude and sign. The prospects of using such superexchange interactions for the investigation of dynamical behaviour in quantum spin systems and for quantum information processing will be outlined in the talk. In addition we present results on the dynamical resolved co-tunnelling of repulsively bound atom pairs in optical superlattices and show how by using ``Coulomb-blockade'' type tunnelling resonance one can count atoms one by one to determine their number statistics in the lattice potential. Finally, latest results on ultracold Fermions and Bose-Fermi mixtures in optical lattices will be presented. [Preview Abstract] |
Wednesday, March 12, 2008 9:48AM - 10:24AM |
P7.00004: Probing and controlling quantum magnetism with ultra-cold atoms Invited Speaker: By loading spinor atoms in optical lattices it is now possible to experimentally implement quantum spin models. These systems allow the investigation of quantum magnetism ~ in strongly correlated systems within a controlled environment. In this talk we will describe a novel approach~to prepare, detect and control super-exchange interactions in ultra-cold~spinor atoms in optical superlattices [1]. Recently this approach was used for the first experimental realization of super-exchange interactions in ultra-cold atoms [2]. The many-body dynamics arising from the coherent coupling between singlet-triplet pairs in adjacent double-wells will be also discussed. ~In particular, we will describe how it can lead to the formation of frustrated spin states with a high degree of multi-particle entanglement. Finally, we will present an extension of this approach to prepare and detect d-wave pairing in an array of coupled plaquettes. \newline ~[1] A. M. Rey, V. Gritsev,I. Bloch, E. Demler, and M. D. Lukin, PRL 99, 140601 (2007). \newline ~[2] S. Trotzky, P. Cheinet, S. Folling, M. Feld, U. Schnorrberger, A.M. Rey, A. Polkovnikov, E. Demler, M. D. Lukin, and I. Bloch., submitted for publication. [Preview Abstract] |
Wednesday, March 12, 2008 10:24AM - 11:00AM |
P7.00005: Heteronuclear Molecules in a 3D Optical Lattice Invited Speaker: The production of ultracold polar molecular samples is a long standing goal of AMO and ultracold physics. The interest is motivated by novel quantum gases with anisotropic interactions between these polar molecules, by applications in quantum computation and simulation which benefit from the long-range interaction as well as by perspectives of measuring a T-violating permanent electric dipole moment of the electron in such a polar molecular system. While a lot of work has been done on direct cooling of polar molecules, a second proposed route to the production of ultracold polar molecules starts with ultracold atomic samples, where tremendous progress has been made in recent years, and assembles an ultracold atom mixture into weakly bound heteronuclear Feshbach molecules. These could then be transferred into the absolute internal molecular ground state using coherent Raman schemes. As a crucial step in this approach, we report on the first production of ultracold long-lived heteronuclear molecules. The molecules are associated from a quantum degenerate mixture of fermionic $^{40}$K and bosonic $^{87}$Rb atoms loaded into a 3D optical lattice. The binding energy of the heteronuclear molecules is precisely determined by rf spectroscopy and compared to a theoretical model based on a pseudopotential approach. We also characterize both the lifetime of the sample and the efficiency of rf association; comparison to the pseudopotential model results in excellent agreement. [Preview Abstract] |
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