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 L4: Cold Atoms and Molecules |
Hide Abstracts |
Chair: Charles Sukenik, Old Dominion University Room: Clark Hall 108 |
Thursday, May 21, 2009 2:00PM - 2:12PM |
L4.00001: Manipulation of trapped atoms on cryogenic atom chips Adrian Lupascu, Andreas Emmert, Jonas Mlynek, Cedric Roux, Gilles Nogues, Michel Brune, Jean-Michel Raimond, Serge Haroche Atom chips are flexible tools for trapping and manipulation of neutral atoms. We use a superconducting atom chip to trap 87Rb atoms [1]. Due to the cryogenic temperatures, the vacuum conditions are improved, resulting in very long trapping lifetime, in the 10 minutes range. The lifetime of trapped atoms near metallic structures is limited by Johnson-Nyquist noise at the surface. We study the lifetime as a function of the distance between the atoms and a gold surface. We find longer times than in similar room temperature experiments, in good agreement with theoretical predictions [2]. For a superconducting surface, one expects a further increase, by several orders of magnitude. In the long term, we intend to use a cryogenic atom chip for deterministic preparation of long- lived single Rydberg atoms, by use of dipole blockade. We present preliminary results on the spectroscopy of Rydberg atoms on the superconducting atom chip. [1] T. Nirrengarten \textit{et }al, PRL 97, 200405 (2006). [2] A. Emmert \textit{ et al}, EPJD (2009). [Preview Abstract] |
Thursday, May 21, 2009 2:12PM - 2:24PM |
L4.00002: Effects of Optical Excitation on the Lifetime of Electrostatically Trapped NaCs Amy Wakim, Patrick Zabawa, Chris Haimberger, Jan Kleinert, Nicholas P. Bigelow $X^1\Sigma \quad v=0-23$ molecules are formed via photoassociation from two overlapped dark-spot MOTs. The ultracold polar molecules are continuously loaded into the TWIST (Thin Wire ElectroStatic Trap) and detected via single color REMPI (Resonance Enhanced Multi-Photon Ionization). During the trapping phase, all light to the chamber is extinguished including all MOT and photoassociation beams to avoid optical pumping effects. Under these conditions, the TWIST has an effective lifetime of 330ms. We will present investigations of the effect of an optical pumping pulse during the trapping phase which can drastically extend the lifetime to 1s. [Preview Abstract] |
Thursday, May 21, 2009 2:24PM - 2:36PM |
L4.00003: Electric manipulation of ultracold polar $^{40}$K$^{87}$Rb molecules in a magnetic field Goulven Qu{\'e}m{\'e}ner, John Bohn Ultracold fermionic polar molecules of $^{40}$K$^{87}$Rb in their absolute rovibronic ground state $(v=0,n=0,^1\Sigma)$ have been created recently~[1] in a magnetic trap and open new perspectives to create fermionic degenerate gases of polar molecules. To achieve this goal, it is very important to understand the collisional properties of such molecules under magnetic and electric fields. In our presentation, we investigate ground state fermionic $^{40}$K$^{87}$Rb + $^{40}$K$^{87}$Rb collisions in the presence of a magnetic field and explore the possibility to control these collisions when an electric field is applied. We will explore the main physical processes that can lead to such manipulation. This problem is complicated by the Zeeman and Stark splitting of all levels of the polar molecules and by the possibility of forming $^{40}$K$_2$ + $^{87}$Rb$_2$ chemical products. \\ \\ 1 - K.-K. Ni, S. Ospelkaus, M. H. G. de Miranda, A. Pe'er, B. Neyenhuis, J. J. Zirbel, S. Kotochigova, P. S. Julienne, D. S. Jin, and J. Ye, Science {\bf 322}, 231 (2008). [Preview Abstract] |
Thursday, May 21, 2009 2:36PM - 2:48PM |
L4.00004: Using an optical lattice to preform KRb molecules and enhance the efficiency of ultracold polar molecule formation James Freericks, Maciej Maska, Romuald Lemanski, Paul Julienne, Thomas Hanna We will discuss recent computational work that employs both direct quantum Monte Carlo simulation and inhomogeneous dynamical mean-field theory to study the efficiency of preforming KRb pairs in an optical lattice. We will describe how to optimize the efficiency by adjusting the lattice depth and the interspecies interaction (via the Feshbach resonance) with parameters specific for fermionic $^{40}$K and bosonic $^{87}$Rb (since the ground-state dipolar molecule has already been formed from those atoms in free space). We work with a deep enough lattice that the K atoms are mobile, but the Rb atoms are localized, so the system is described by the spinless Falicov-Kimball model on a two-dimensional lattice. We also calculate the entropy and estimate the temperature that one can achieve by cooling the atoms and adiabatically turning on the lattice. [Preview Abstract] |
Thursday, May 21, 2009 2:48PM - 3:00PM |
L4.00005: Towards fundamental understanding of ultracold KRb Svetlana Kotochigova The recent formation of ultracold KRb molecules in their absolute rovibrational ground state [1] has created great promise for study of collective phenomena that rely on the long-range interactions between polar molecules. Here we discuss the theoretical analysis of various essential properties of the KRb molecules [2] that accompanied these experimental advances. This analysis is based on multi-channel bound-state calculations of both ground and excited electronic states. We have found that the theoretical hyperfine and Zeeman mixed X$^1\Sigma^+$ and a$^3\Sigma^+$ vibrational structure shows excellent agreement with the experimentally observed structure. In addition, multi-channel calculations of the rovibrational structure of the excited state potentials have allowed us to find the optimal transitions to the lowest $v$=0 vibrational levels. Finally, we examine the dynamic polarizability of vibrationally cold KRb molecules as a function of laser frequency. Based on this knowledge, laser frequencies can be selected to minimize decoherence from loss of molecules due to spontaneous or laser-induced transitions. [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 {\bf 322}, 231 (2008). [2] S. Kotochigova, E. Tiesinga, and P. S. Julienne, submitted to New J. Phys. (2009). [Preview Abstract] |
Thursday, May 21, 2009 3:00PM - 3:12PM |
L4.00006: Collisions of cold polar molecules in a microwave cavity T.V. Tscherbul, S.V. Alyabyshev, R.V. Krems We present accurate quantum calculations for low-temperature collisions of polar molecules and atoms in a microwave laser field. The effects of the radiation field on the collision dynamics are described exactly using the dressed-state formalism of quantum optics. Our calculations identify new mechanisms for rotational relaxation of molecules placed in a microwave cavity and indicate that molecular collisions at temperatures below 0.5 K can be efficiently manipulated with microwave laser fields of moderate strength. [Preview Abstract] |
Thursday, May 21, 2009 3:12PM - 3:24PM |
L4.00007: Cryogenic beam sources: towards trapping and cooling polar molecules David Glenn, Edward Shuman, John Barry, David DeMille We report on the continuing development of a cryogenic helium buffer-gas cooled molecular beam source. We have carefully characterized the properties of this source for several molecular species and in a variety of buffer-gas flow regimes, ranging from the effusive (thermal mean velocity, moderate flux), to the deeply hydrodynamic (large forward velocity, high-flux, high collimation). We describe efforts to electrostatically guide molecules from this source, as well as investigations into the possibility of performing transverse and/or longitudinal laser cooling on the beam. We also describe efforts towards confining molecules from this source in a microwave-frequency quasi-optical dipole trap. [Preview Abstract] |
Thursday, May 21, 2009 3:24PM - 3:36PM |
L4.00008: Prospects for sympathetic cooling of optically stark decelerated molecules Paolo Barletta, Jonathan Tennyson, Peter F. Barker A novel approach has recently been proposed for producing ultra-cold molecules by sympathetic cooling with optically co-trapped rare gas (Rg) atoms [1]. For an efficient planning and realization of the experiment theoretical determination of atom-molecule cross sections at ultra-low energies is very important. In this contribution I will present calculations of scattering lengths and cross sections for he Rg-H$_2$ and Rg-benzene complexes (Rg=He,Ne,Ar,Kr,Xe), with particular emphasis on Ar and Kr. H$_2$ and benzene are considered in their lowest vibrational-rotational states. A direct Monte Carlo simulation of the dynamics of the cooling process has been made by means of the Bird method. This simulation will enable the optimization of the experimental apparatus, and to test the cooling capability of the different Rg gases. [1] P. Barletta, J. Tennyson, P.F. Barker, {\it Phys. Rev. A}, {\bf 78}, 052707 (2008). [Preview Abstract] |
Thursday, May 21, 2009 3:36PM - 3:48PM |
L4.00009: Generation of Cold Molecular Beams of CaF and BaF Eric Vyskocil, Susumu Kuma, Takamasa Momose The field of ultracold molecules continues to generate a large amount of interest with many applications. Significant enhancement of the electric dipole moment of the electron is expected for some molecular systems such as YbF, PbO, and BaF [1]. Here, we report a generation of cold molecular beam of $^{40}$Ca$^{19}$F and $^{138}$Ba$^{19}$F using a hexapole velocity filter. The electrostatic velocity filter with a quadruple guide has been proposed as a source of cold polar molecules [2]. Using an electrostatic hexapole guide combined with laser ablation, we have generated a cold molecular beam of CaF with a longitudinal temperature in the 100 mK range. Target molecules produced by laser ablation of CaF$_{2}$ (BaF$_{2})$ are cooled by cold pulsed Helium gas and introduced into the hexapole, which filters low field seeking molecules with low longitudinal velocity. The conditions of the cold pulsed Helium beam and hexapole are varied to optimize the mass signal of cold molecules. Further cooling schemes down to the $\mu $K range will also be discussed. [1] E. A. Hinds, Phys. Scripta, T70, 34 (1997). [2] S. A. Rangwala et al. Phys. Rev. A67, 043406 (2003). [Preview Abstract] |
Thursday, May 21, 2009 3:48PM - 4:00PM |
L4.00010: Towards chirped optical Stark deceleration of molecules Nicholas Coppendale, Peter Douglas, Lei Wang, Peter Barker Optical Stark deceleration can be used to create cold stationary molecules. This scheme uses deep potentials, created by the interaction of the optical field with the induced dipole moment, to trap molecules within a cold molecular beam and transport them to zero velocity. This can be accomplished using the periodic potential of a constant velocity optical lattice created by the interference of strong laser fields (10$^{10} - 10^{12}$ W cm$^{-2}$) [1]. We describe the experimental realisation of chirped optical Stark deceleration which uses a rapidly decelerating optical lattice to slow molecules with a narrower energy spread. The lattice beams are created by a unique laser system that produces two, high energy, laser pulses whose frequency and intensity can be well controlled over durations of greater than 100 ns. The beams are created by amplifying a single rapidly tuneable Nd:YVO4 microchip laser at 1064 nm. Linear frequency chirps of up to 1 GHz have been demonstrated over 150 ns which are suitable for deceleration of most molecular species contained within a molecular of beam of xenon. We will describe this laser system and initial deceleration experiments of molecular hydrogen, as well as trapping and sympathetic cooling experiments with ultra-cold atoms.\\[3pt] [1] R. Fulton, A. I. Bishop, M. N. Shneider, and P. F. Barker, Nature, Physics, 2006, 2, 465. [Preview Abstract] |
Thursday, May 21, 2009 4:00PM - 4:12PM |
L4.00011: Towards cold collisions between dipolar OH and ND$_{3}$ molecules within a permanent magnetic trap Brian Sawyer, Benjamin Stuhl, Mark Yeo, Dajun Wang, Jun Ye Progress in the field of cold molecules promises many new and exciting applications. The long range dipole-dipole interactions between cold polar molecules may be exploited to control intermolecular elastic/inelastic scattering processes with external electric fields. This same interaction could also be used to study long-range dynamics in condensed matter physics. Our group has successfully trapped Stark-decelerated OH molecules within a permanent magnetic trap at a temperature of 70 mK and density of 10$^{6}$ cm$^{-3}$. The trapped molecules were used in collision studies with external He and D$_{2}$ supersonic beams at temperatures of $\sim $80 K, yielding evidence of quantum threshold scattering and resonant energy transfer between colliding particles. We will report progress towards observation of cold collisions ($\sim $ 1 K) between magnetically trapped OH and buffer-gas cooled, electrostatically-guided ND$_{3}$ molecules. Collision cross sections between OH and ND$_{3}$ will be investigated within a variable external electric field superimposed on the OH magnetic trap. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700