### Session B1: Recent Developments in Optical Lattice Physics

Chair: Randy Hulet, Rice University
Room: Nittany Lion Inn Ballroom CDE

 Wednesday, May 28, 2008 11:00AM - 11:36AM B1.00001: Spinning Atoms with the Orbital Angular Momentum of Light Invited Speaker: William D. Phillips Atoms in a moving optical lattice can Bragg reflect from that lattice in a completely coherent manner. This transfer of momentum between light and atoms is one of the important tools used to manipulate atoms coherently. Light can also coherently change the internal state of an atom, and the polarization of the light often controls how the angular momentum state of the atoms changes. Light can also carry angular momentum that is not associated with its polarization---orbital angular momentum that is associated with the spatial mode of the light field. We use that orbital angular momentum to coherently manipulate the circulation state of a coherent cloud of atoms (a Bose-Einstein condensate.) The process, rotational Bragg scattering, uses a moving optical lattice in which one of the laser beams forming the lattice is a Laguerre-Gauss beam carrying orbital angular momentum. Using this technique we can deterministically create vortices with various quantized values of angular momentum. Atom interferometry confirms the coherence of this process. By holding a BEC in a toroidal trap and inducing circulation via this rotational Bragg process, we create persistent atom currents that survive more than an order of magnitude longer than similarly created vortices. We propose that with such a geometry we may create atomic analogs of superconducting circuits containing Josephson junctions. Wednesday, May 28, 2008 11:36AM - 12:12PM B1.00002: Towards Quantum Magnetism with Ultracold Quantum Gases in Optical Lattices Invited Speaker: Immanuel Bloch 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-tunneling of repulsively bound atom pairs in optical superlattices and show how by using Coulomb-blockade'' type tunneling 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. Wednesday, May 28, 2008 12:12PM - 12:48PM B1.00003: Fermions and bosons in optical lattices Invited Speaker: Michael Koehl We report on the preparation and study of fermionic and bosonic atoms in optical lattices. In a three-dimensional optical lattice the atoms realize a Hubbard model which is a fundamental model to describe the physics of strongly correlated condensed matter systems. The full phase diagram of the Hubbard model includes fascinating phases exhibiting strong correlations such as magnetic order, superconductivity and a Mott insulator. Mixtures of bosonic and fermionic atoms represent a fascinating extension of atomic lattice gases in which two systems of fundamentally different quantum statistics are interlinked. We study the mutual influence of fermions and bosons in optical lattice and investigate how the presence of the fermions modifies the coherence properties of the bosonic atoms. Wednesday, May 28, 2008 12:48PM - 1:24PM B1.00004: Probing and controlling quantum magnetism with ultra-cold atoms Invited Speaker: Ana Maria Rey By loading spinor atoms in optical lattices it is now possible to experimentally implement quantum spin models in a controlled environment, and to investigate quantum magnetism in strongly correlated systems. In this talk we will describe a novel approach to prepare, detect and control super-exchange interactions in ultracold spinor atoms loaded in optical superlattices [1]. Recently this approach was used for the first experimental observation 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 how it can lead to the formation of spin states with a high degree of multi-particle entanglement. Finally, we will present an extension of this approach to prepare and detect in a controllable way d-wave superfluidity in an array of weakly coupled plaquettes loaded with fermionic atoms. \newline \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, Science 319, 295 (2008)