Bulletin of the American Physical Society
42nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 56, Number 5
Monday–Friday, June 13–17, 2011; Atlanta, Georgia
Session M3: Cold Collisions and Photoassociation |
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Chair: Jose D'Incao, JILA and University of Colorado Room: A703 |
Thursday, June 16, 2011 8:00AM - 8:12AM |
M3.00001: Photoassociation of ultracold NaCs via (4)$\Omega$=1 yields deeply-bound, highly polar X$^{1}\Sigma^{+}$ states Amy Wakim, Patrick Zabawa, N.P. Bigelow We determine the presence of a previously unknown avoided crossing between the (3)$\Omega$=1 and (4)$\Omega$=1 long-range states which may contribute to the production of deeply bound molecules populating X$^{1}\Sigma^{+}$(v = 4-6, 8, 9, 11, 13, 15-17, 19, 21, 23-25, 31). A combination of pulsed depletion spectroscopy and photoassociation (PA) spectroscopy is utilized to assign PA resonances, illuminate the character of the potential energy curves involved, and label the rotational and vibrational population of the final distribution. We present an improved C$_{6}$ coefficient for the (4)$\Omega$=1 and the assignments for all twenty-two PA resonances detuned from the Cs 6$^{2}$P$_{3/2}$ asymptote. [Preview Abstract] |
Thursday, June 16, 2011 8:12AM - 8:24AM |
M3.00002: ABSTRACT WITHDRAWN |
Thursday, June 16, 2011 8:24AM - 8:36AM |
M3.00003: Investigation of a resonantly coupled photoassociation resonance for production of ultracold, polar molecules in the absolute vibrational ground state Patrick Zabawa, Amy Wakim, Marek Haruza, Nicholas Bigelow We report on the discovery of a photoassociation (PA) resonance in NaCs which efficiently populates $X^{1}\Sigma^{+} (v=0)$, and on our progress in detecting these molecules. We found the resonance while performing PA spectroscopy detuned from the Cs $6^{2}$P$_{1/2}$ asymptote, and we discuss our analysis of this spectrum. The effeciency of the observed PA resonance in producing deeply bound $X^{1}\Sigma^{+}$ molecules is due to resonant coupling with $v = 17$ in the $B^{1}\Pi$ electronic state. The rotational quanta 0-4 are coupled, though the strongest coupling appears in J = 1 and 2. In order to detect the absolute vibrational ground state, we plan to perform two-color Resonance Enhanced Multi-Photon Ionization using the fundamental and 2nd harmonic output of a KDP crystal pumped with an infrared pulsed dye laser. We also discuss the prospects for trapping and accumulating molecules in the vibrational ground state. [Preview Abstract] |
Thursday, June 16, 2011 8:36AM - 8:48AM |
M3.00004: Long-Range Trilobite-like Cs Molecules in a Crossed 1064 nm Dipole Trap Jonathan Tallant, Donald Booth, Luis Marcassa, Bruno Marangoni, James Shaffer In the past, our group has observed long-range Rydberg atom- Rydberg atom molecules created within a MOT. The density required to observe such molecules can be relatively low, $\la 10^{10}$ cm$^{-3}$ because the bound states exist at internuclear separations between $\sim 3 \mu$m and $\sim 9 \mu$m. The increase in density to $\sim 10^{13}$ cm$^{-3}$ in a crossed dipole trap allows for new types of molecule formation which are inefficient in lower density traps, like the MOT. In particular, new bonding mechanisms may arise from the low-energy scattering of a Rydberg atom electron (with negative scattering length) from a ground state atom, so called trilobite and trilobite-like molecules. We present data on the spectroscopic identification of Cs $n^{2}S_{1/2}$ + $6^{2}S_ {1/2}$ trilobite-like molecules. Progress on resolving the vibrational structure of both singlet and triplet species will be presented. We acknowledge funding from ARO (W911-NF-08-1-0257), NSF (PHY- 0855324) and NSF (OISE-0756321). [Preview Abstract] |
Thursday, June 16, 2011 8:48AM - 9:00AM |
M3.00005: Sympathetic cooling in an optically trapped mixture of alkali and spin-singlet atoms Anders Hansen, Alexander Khramov, William Dowd, Alan Jamison, Vladyslav Ivanov, Frank M\"unchow, Subhadeep Gupta We report on the realization of a stable mixture of ultracold lithium and ytterbium atoms confined in a far-off-resonance optical dipole trap. We observe sympathetic cooling of $^{6}$Li by $^{174}$Yb and extract the s-wave scattering length magnitude $|a_{^{6}Li-^{174}Yb}|$ from the rate of inter-species thermalization. Using forced evaporative cooling of $^{174}$Yb, we achieve reduction of the $^{6}$Li temperature to below the Fermi temperature, purely through inter-species sympathetic cooling. These observations constitute a starting point for experiments with simultaneously quantum degenerate species, and pave the way toward synthesis of paramagnetic, polar molecules. [Ref. arXiv:1101.5142] [Preview Abstract] |
Thursday, June 16, 2011 9:00AM - 9:12AM |
M3.00006: Interactions between ultra-cold ions and neutral atoms/Bose-Einstein condensates David A. Anderson, Andrew T. Cadotte, Rachel E. Sapiro, Georg Raithel Recently, there has been growing theoretical and experimental interest in understanding interactions between ultra-cold, charged impurities and Bose-Einstein condensates (BEC). The phenomena one may expect to find include quantum charge diffusion [1] and the formation of mesoscopic molecular ions via recombination of BEC atoms by ion-induced polarization potentials [2]. Here, we present progress towards experimental studies of these phenomena using a $^{87}$Rb BEC setup. In these studies it is paramount that the ion have low kinetic energy and a sufficiently long dwell time in the ultra-cold neutral atom sample/BEC ($\sim$100 $\mu$s). These conditions are met by creating free ions via photoionization of $^{87}$Rb atoms into low values of the single atom energy continuum and by minimizing stray electric fields in the interaction region. We are capable of spatially imaging ion distributions, ion counting, and acquiring ion time-of-flight information. These are achieved by extracting the ions using an electric field from a small tip-like structure, guiding them through an ion-lens system and into a multichannel plate. Ion trajectories are modeled for our system to guide experimental imaging parameters. [1] R. Cote, Phys. Rev. Lett. {\bf{85}} 5316 (2000); [2] R. Cote et al., Phys. Rev. Lett. {\bf{89}} 093001 (2002). We acknowledge support by the AFOSR. [Preview Abstract] |
Thursday, June 16, 2011 9:12AM - 9:24AM |
M3.00007: Anisotropy in the Interactions of Ultracold Dysprosium Svetlana Kotochigova, Alexander Petrov The ground $4{\rm f}^{10}6{\rm s}^2$ configuration of atomic dysprosium has an unfilled 4f$^{10}$ shell lying beneath a closed 6s$^2$ shell. This so-called ``submerged-shell'' atom has a large orbital ($L$ = 6) and total ($J$ = 8) electron angular momenta and, consequently, an extremely large magnetic moment of $10\mu_B$. Only recently the first laser cooling and trapping experiment of dysprosium atoms has been reported [1]. The experiment suggested that the anisotropy from the submerged shell and magnetic moment plays a significant role in the interactions of dysprosium atoms. Here, we explore the anisotropies from the electrostatic dispersion and magnetic dipole-dipole interactions. We use a relativistic configuration interaction valence-bond method to obtain short-range chemical potentials. Dispersion coefficients have been calculated using known atomic data. Comparison of the strengths of dispersion and magnetic dipole interactions shows that the anisotropy in the dispersion dominates for atomic separations less than 50 bohr and can lead to a rapid reorientation of the Dy angular momenta.\\[4pt] [1] M. Lu, S. Ho Youn, and B. Lev, Phys. Rev. Lett. {\bf 104}, 063001 (2010). [Preview Abstract] |
Thursday, June 16, 2011 9:24AM - 9:36AM |
M3.00008: Bound States of Two Bosons in an Optical Lattice Near an Association Resonance Jerome Sanders, Otim Odong, Juha Javanainen, Matt Mackie We theoretically examine the bound states of two bosons near a Feshbach or photoassociation resonance, focusing on the Bose-Hubbard model in one dimension. Whereas the usual atoms-only theory with a tunable scattering length yields one bound state dimer for either attractive or repulsive atom-atom interactions, an atom-molecule theory may give two bound states that represent attractively and repulsively bound dimers occurring simultaneously. Such unusual molecular physics may be observable for an atom-molecule coupling strength comparable to the width of the dissociation continuum of the lattice dimer. We identify narrow Feshbach and photoassociation resonances as potential candidates for experiments. [Preview Abstract] |
Thursday, June 16, 2011 9:36AM - 9:48AM |
M3.00009: Towards the experimental accuracy deperturbation analysis of the fully mixed $A^{1}\Sigma^{+}$ and $b^{3}\Pi$ states of Rb$_{2}$, Cs$_{2}$ and RbCs molecules Andrey Stolyarov, Thomas Bergeman The laser production and manipulation of the ultracold molecular assembles would be greatly facilitated by accurate knowledge of the structure and dynamic properties of the electronic states involved. In spite of the recent progress in the systematic spectroscopic investigation of the promising diatomic species such as Rb$_{2}$, Cs$_{2}$ and RbCs, the reduction of the raw experimental data available for fully mixed A$^{1}\Sigma^{+}$ and $b^{3}\Pi$ states to the precise structure parameters (potential and interaction matrix elements) is very challenging and still unambiguous procedure. We present here a review of physical models and numerical recipes currently developed for the comprehensive deperturbation treatment of the strongly coupled diatomic states in a wide range of excitation energy and internuclear distance. The crucial role of ab initio calculations on the spin-orbit coupling matrix elements in the deperturbation analysis is demonstrated. The interpolation and extrapolation properties of the resulting non-adiabatic models are discussed with respect to accuracy required for the adequate reproduction of experimental data sets. [Preview Abstract] |
Thursday, June 16, 2011 9:48AM - 10:00AM |
M3.00010: 1D scattering experiments with ultra-cold atoms: transient enhancement of high momenta Rockson Chang, Chris Ellenor, Mirco Siercke, Shreyas Potnis, Aephraim Steinberg During the scattering of a particle from a repulsive potential, the particle can exhibit an enhancement of high momentum components. This effect is transient in the sense that it only exists when there is an overlap between the particle's wavefunction and the scattering potential, and is inherently a quantum mechanical phenomenon. This effect has been shown to be strongest for scattering potentials that are weak such that the wavepacket is entirely transmitted [1]. In our experiment we use an ultra-cold gas interacting with a thin optical dipole barrier to observe this effect. If time permits, we will discuss experiments in progress to investigate tunneling of our ultra-cold gas in 1D. \\[4pt] [1] S. Brouard and J. G. Muga , Phys. Rev. Lett. \textbf{81}, 2621-2625 (1998) [Preview Abstract] |
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