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 X2: Focus Session: Ultracold Molecules II |
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Chair: Kate Kirby, ITAMP, Harvard University Room: Gilmer Hall 130 |
Saturday, May 23, 2009 10:30AM - 11:00AM |
X2.00001: Understanding ultracold polar molecules Invited Speaker: The successful production of a dense sample of ultracold ground state KRb polar molecules [1] opens the door to a new era of research with dipolar gases and lattices of such species. This feat was achieved by first associating a K and a Rb atom to make a weakly bound Feshbach molecule and then coherently transferring the population to the ground vibrational level of the molecule. This talk focuses on theoretical issues associated with making and using ultracold polar molecules, using KRb as an example [2]. Full understanding of this species and the processes by which it is made requires taking advantage of accurate molecular potentials [3], \textit{ab initio} calculations [4], and the properties of the long-range potential. A highly accurate model is available for KRb for all bound states below the ground state separated atom limit and could be constructed for other species. The next step is to develop an understanding of the interactions between polar molecules, and their control in the ultracold domain. Understanding long-range interactions and threshold resonances will be crucial for future work. [1] K.-K. Ni, \textit{et al}, Science 322, 231(2008). [2] P. S. Julienne, arXiv:0812:1233. [3] Pashov \textit{et al}., Phys. Rev. A76, 022511 (2007). [4] S. Kotochigova, \textit{et al}., arXiv:0901.1486. [Preview Abstract] |
Saturday, May 23, 2009 11:00AM - 11:30AM |
X2.00002: Experiments with Stark decelerated and trapped molecules Invited Speaker: Over the last years our group has been developing methods to get improved control over the velocity of molecules in a molecular beam [1]. With the Stark decelerator, a part of a molecular beam can be selected and transferred to any arbitrary velocity, producing bunches of state-selected molecules with a computer-controlled velocity and with longitudinal temperatures as low as a few mK. So far, this new molecular beam technology has been used mainly to decelerate packets of molecules to standstill, and to subsequently confine these molecules in a trap. We will report on various experiments that have been performed with these samples of trapped molecules. Stark decelerated molecular beams also hold great promise in molecular beam scattering experiments. In a crossed-beam configuration, these beams offer the revolutionary capability to study elastic or inelastic and reactive scattering as a function of the continuously variable collision energy with a high intrinsic energy resolution. We will report on the first scattering experiment using a Stark decelerated beam of OH radicals [2], and our progress on a new crossed beam machine containing two Stark decelerators under 90 degrees crossing angle. \\[4pt] [1] S.Y.T. van de Meerakker et al., Nature Physics 4, 595 (2008). \\[0pt] [2] J.J. Gilijamse et al., Science 313, 1617 (2006). [Preview Abstract] |
Saturday, May 23, 2009 11:30AM - 11:42AM |
X2.00003: Quantum phases of strongly interacting polar molecules Guido Pupillo, Andrea Micheli, Michael Ortner, Peter Zoller We discuss how to realize novel quantum phases and quantum simulations with cold polar molecules prepared in the electronic and vibrational groundstate. [Preview Abstract] |
Saturday, May 23, 2009 11:42AM - 11:54AM |
X2.00004: Photonionization Spectroscopy of Electrostatically Trapped, Ultracold Polar Molecules in the Electronic Ground State Patrick Zabawa, Amy Wakim, Christopher Haimberger, Jan Kleinert, Nicholas P. Bigelow We have observed ultracold, electrostatically trapped NaCs occupying a wide range of vibrational levels in the $X^1\Sigma ^+$ state. Ultracold NaCs is prepared from magneto-optical traps (MOTs) via photoassociation with a laser field detuned from the Cs $6S_{1/2} -6P_{3/2} $ transition. Rotationally cold (from $J=1$ to $J\approx 6)$ molecules are continuously loaded into a Thin Wire Electrostatic Trap (TWIST) which is spatially mode-matched with the MOTs. Using Resonance Enhanced Multi-Photon Ionization (REMPI), bound-bound transitions are detected between 16400 and 18200 $cm^{-1}$. The creation of both bound molecular ions and photofragments from trapped molecules occurs at these ionization energies, which is consistent with both two- and three-photon excitations from the ground state. An analysis of the spectrum indicates the presence of trapped $X^1\Sigma ^+$ molecules populating vibrational levels from $v\approx 23$ down to the ground state. [Preview Abstract] |
Saturday, May 23, 2009 11:54AM - 12:06PM |
X2.00005: Formation of weakly bound molecules in buffer-gas cooling experiments with silver atoms N. Brahms, T.V. Tscherbul, P. Zhang, J. Klos, Y. Au, H.R. Sadeghpour, A. Dalgarno, J.M. Doyle, T.G. Walker The rate for spin relaxation of Ag atoms in cryogenic $^3$He gas increases by two orders of magnitude with decreasing temperature from 600 to 300 mK. We argue that the anomalous behavior might be a signature for the formation and decay of weakly bound AgHe dimers. Ab initio calculations of binding energies show that at a temperature of 300 mK, more than 5\% of Ag atoms are associated into AgHe molecules. The AgHe dimers undergo rapid spin relaxation in collisions with He or Ag atoms, and the temperature dependence of the spin relaxation rate follows that of the chemical equilibrium coefficient for three-body recombination Ag + He + He $\to$ AgHe + He. The impact of weakly bound molecules on cryogenic and sympathetic cooling experiments is discussed. Phys. Rev.Lett. {\bf 101}, 103002 (2008). [Preview Abstract] |
Saturday, May 23, 2009 12:06PM - 12:18PM |
X2.00006: Molecular cooling by optical pumping with shaped femtosecond pulses Daniel Comparat, Dimitris Sofikitis, Andr\'ea Fioretti, Xiaolin Li, Ridha Horchani, Pierre Pillet, Maria Allegrini, Marin Pichler, Sebastien Weber, B\'eatrice Chatel Vibrational cooling of translationally cold Cs$_{2}$ molecules into a selected vibrational level v = 0,1,2 or v=7 of the singlet X$^{1}\Sigma _{g}^{+}$ ground electronic state has been realized. Our method is based on repeated optical pumping by laser light with a spectrum broad enough to excite all populated vibrational levels but frequency-shaped in such a way to eliminate transitions from the chosen v level, in which molecules accumulate. Using ultrashort pulse shaping techniques based on Liquid Crystal spatial light modulator a large fraction of the initial molecules is transfered into a single selected vibrational level such as v = 0,1, 2 and 7. Limitations of the method as well as the possible extension to rotational and translational cooling will also be discussed. [Preview Abstract] |
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