Bulletin of the American Physical Society
41st Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 55, Number 5
Tuesday–Saturday, May 25–29, 2010; Houston, Texas
Session X2: Focus Session: Cold and Ultracold Molecules |
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Chair: Susanne Yellin, University of Connecticut Room: Imperial Center |
Saturday, May 29, 2010 10:30AM - 11:00AM |
X2.00001: Strongly correlated phases with moderately strong dipole moments Invited Speaker: Ultracold polar molecules offer the possibility of exploring quantum gases with interparticle interactions that are long-range, and spatially anisotropic. While several novel many-body phenomena have been predicted to occur for strong dipole-dipole interactions, in this talk we focus on strongly correlated phases which can be obtained with comparatively moderate strengths of interactions, such as those found with KRb molecules. [Preview Abstract] |
Saturday, May 29, 2010 11:00AM - 11:30AM |
X2.00002: Ultracold ground state molecules in an optical lattice Invited Speaker: We produce ultracold and dense samples of rovibrational ground state (RGS) molecules near quantum degeneracy. We first associate dimer molecules out of a lattice-based Mott-insulator state loaded from an atomic BEC and then coherently transfer the molecules to the RGS by a multiphoton STIRAP process. With an overall efficiency of 50\%, we prepare a molecular quantum gas state in which every second site of an optical lattice is occupied with a RGS molecule.\footnote{An ultracold, high-density sample of rovibronic ground-state molecules in an optical lattice, J.G. Danzl et al., arXiv:0909.4700 (2009), to appear in Nature Physics.} We expect that, with further optimization of the transfer procedure, a BEC of RGS molecules is possible. [Preview Abstract] |
Saturday, May 29, 2010 11:30AM - 11:42AM |
X2.00003: All-Optical Scheme to Produce Quantum Degenerate Dipolar Molecules in the Vibronic Ground State Matt Mackie, Catherine DeBrosse We consider two-color heteronuclear photoassociation of Bose-condensed atoms into dipolar molecules in the $J=1$ vibronic ground state, where a free-ground laser couples atoms directly to the ground state and a free-bound laser couples the atoms to an electronically-excited state. The addition of the excited state creates a second pathway for creating ground state molecules, leading to quantum interference between direct photoassociation and photoassociation via the excited molecular state, as well as a dispersive-like shift of the free-ground resonance position. Using LiNa as an example, these results are shown to depend on the detuning and intensity of the free-bound laser, as well as the semi-classical size of both molecular states. Despite strong enhancement, coherent conversion to the LiNa vibronic ground state is possible only in a limited regime near the free-bound resonance. [Preview Abstract] |
Saturday, May 29, 2010 11:42AM - 11:54AM |
X2.00004: Fermionic molecule formation by ramps across Fano-Feshbach resonance Chen Zhang, Shinichi Watanabe, Chris Greene This project is a theoretical investigation of properties of a gas of fermionic diatomic molecule, including the molecule formation from bosonic $^{87}$Rb and fermionic $^{40}$K gases by magnetic field ramps across a Fano-Feshbach resonance. We also studied molecule-atom oscillatory quantum beats created during experiments with time-dependent magnetic field ramps. We have approached the problem from various viewpoints: including quantum mechanical pairing theories, the adiabatic thermodynamic limit estimation, and statistical Monte Carlo simulations. Preliminary results will be shown at the meeting including a comparison with available experimental data [1]. \\[4pt] [1] M. L. Olsen, J. D. Perreault, T. D. Cumby, and D. S. Jin, Phys. Rev. A \textbf{80}, 030701(2009) [Preview Abstract] |
Saturday, May 29, 2010 11:54AM - 12:06PM |
X2.00005: Magnetoassociation of KRb Feshbach molecules Tyler Cumby, John Perreault, Ruth Shewmon, Deborah Jin I will discuss experiments in which we study the creation of $^{40}$K$^{87}$Rb Feshbach molecules via magnetoassociation. We measure the molecule number as a function of the magnetic-field sweep rate through the interspecies Feshbach resonance and explore the dependence of association on the initial atom gas conditions. This study of the Feshbach molecule creation process may be relevant to the production of ultracold polar molecules, where magnetoassociated Feshbach molecules can be a crucial first step [1].\\[4pt] [1] K.-K. Ni, S. Ospelkaus, M. H. G. de Miranda, A. Peer, B. Neyenhuis, J. J. Zirbel, S. Kotochigova, P. S. Julienne, D. S. Jin, and J. Ye, Science, 2008, 322, 231- 235. [Preview Abstract] |
Saturday, May 29, 2010 12:06PM - 12:18PM |
X2.00006: Direct laser cooling of a diatomic molecule Edward Shuman, John Barry, Dave DeMille We have experimentally observed transverse laser cooling of the polar, diatomic molecule strontium monofluoride (SrF) using the $X^2\Sigma^+\!\rightarrow\!A^2\Pi_{1/2}$ optical cycling scheme previously demonstrated [1]. In general molecules are not amenable to direct laser cooling because their vibrational and rotational degrees of freedom typically lead to high branching probabilities into a large number of unwanted sublevels. Our scheme takes advantage of SrF's highly diagonal Franck-Condon factors which suppress vibrational branching. We eliminate rotational branching by employing a quasi-cycling $N\!=\!1\! \rightarrow\! N^\prime\!=\!0$ type transition in conjunction with magnetic field remixing of dark Zeeman sublevels. One complication of this scheme is that the large number of $X^2 \Sigma^+$ ground levels in this system leads to a photon scattering rate which is a factor of 3.5 smaller than that of a comparable two-level system. The reduced scattering rate requires that the cooling region be significantly longer than that typically used in atomic systems. \\[4pt] [1] E. S. Shuman, J. F. Barry, D. R. Glenn, and D. P. DeMille, Phys. Rev. Lett. 103, 223001 (2009). [Preview Abstract] |
Saturday, May 29, 2010 12:18PM - 12:30PM |
X2.00007: Preforming molecules of Fermi-Bose light-heavy alkali mixtures to create dense dipolar matter: the strong coupling approach Anzi Hu, Jim Freericks, Maciej Maska, Carl Williams In this talk, we discuss our recent work on using the strong- coupling expansion (perturbation theory in the hopping) to calculate the efficiency of pre-forming molecules of Fermi-Bose light-heavy alkali mixtures (like K-Rb) in an optical lattice. In previous work [1], we have shown that loading the mixture onto a two-dimensional square lattice can dramatically improve the efficiency of pre-forming dipolar molecules. In this talk, we will show that within the strong interaction regime (and at high temperature), the SC expansion is a very economical way to study this problem. The SC approach also enables us to work with much larger system sizes, where boundary effects can be eliminated. This is particularly important at higher temperatures where the boundary effects can significantly affect the results.This approach could be useful for experimentalists to rapidly scan through parameter space to optimize the pre-forming of molecules on the lattice (by choosing the lattice depth and interspecies attraction) prior to the Feschbach sweep and STIRAP process used to make ground- state molecules. [1] J. K. Freericks, \textit{et al}, arXiv:0908.1794v1 [Preview Abstract] |
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