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 K7: Cooling of Atoms and Molecules |
Hide Abstracts |
Chair: Wes Campbell, JQI and University of Maryland Room: A707 |
Wednesday, June 15, 2011 2:00PM - 2:12PM |
K7.00001: Demonstration of a $^{6}$Li magneto-optical trap using the $2S_{1/2}\rightarrow 3P_{3/2}$ transition R.A. Hart, P.M. Duarte, T.L. Yang, R.G. Hulet We demonstrate narrow linewidth laser cooling on the $2S_{1/2}\rightarrow 3P_{3/2}$ transition of $^{6}$Li at 323 nm. Typically, magneto-optical traps (MOTs) of alkali atoms cool on the D2 transition. The linewidth of this transition determines the Doppler limit of cooling which in the case of $^{6}$Li is 140 $\mu$K, given a 5.9 MHz transition linewidth. Due to a lack of resolved hyperfine structure that prohibits polarization gradient cooling, typical Li MOTs reach minimum temperatures near 300 $\mu$K. Cooling on the $2S_{1/2}\rightarrow 3P_{3/2}$ transition, however, allows for a Doppler limit of 20 $\mu$K since the transition linewidth is only 790 kHz. We have implemented this cooling scheme and demonstrate $^{6}$Li MOT temperatures of 65 $\mu$K. The substantially decreased temperature of this MOT enhances loading of the gas into an optical trap. We present our results on the characteristics of the narrow linewidth MOT and our results on the benefits of using this cooling scheme in the preparation of a degenerate gas of fermions. [Preview Abstract] |
Wednesday, June 15, 2011 2:12PM - 2:24PM |
K7.00002: Sub-Doppler Laser Cooling With Planar-Geometry Optics And a Single Laser Beam Paul Griffin, Matthieu Vangeleyn, Erling Riis, Aidan Arnold We have realized a new magneto-optical trap geometry using a single laser beam incident on planar optics. In this arrangement we trap $10^6$ $^{87}$Rb atoms and have achieved temperatures of 40~$\mu$K. We have been inspired by the continued interest in miniaturizing the technology for ultra-cold atomic physics, particularly for applications concerning sensing. Work towards the achievement of small scale, all-integrated magneto-optical traps (MOT) has been very active, such as the realization of MOTs in a microfabricated pyramidal structure. Here we present an new design with significant advantages as a compact source of cold atoms. A triplet of diffraction gratings splits a laser beam such that four beams cross a tetrahedral configuration in the MOT region. This arrangement offers a uniformly balanced radiation pressure area, and becomes suitable for efficient sub-Doppler cooling. The planar configuration offers maximal optical access to the atomic cloud and can be easily turned into an integrated micro-trap, benefiting from standard lithography processes. In addition, a micro-fabricated tetrahedral configuration offers an ideal tool for a high phase stability optical lattice, with the benefit of fixed lattice geometry. [Preview Abstract] |
Wednesday, June 15, 2011 2:24PM - 2:36PM |
K7.00003: Magic-zero wavelengths of alkali-metal atoms and their applications Bindiya Arora, M. S. Safronova, Charles W. Clark We identified wavelengths $\lambda_0$ where the ground state frequency-dependent polarizabilities in alkali-metal atoms are zero. The calculations were carried out using high-precision relativistic all-order method where all single, double, and partial triple excitations of the Dirac-Fock wave functions are included to all orders of perturbation theory. Several magic-zero wavelengths are determined for alkali-metal atoms from Li to Cs, and their uncertainties are estimated. Applications of these magic-zero wavelengths to sympathetic cooling in two-species mixtures of group-II and other more complicated atoms with alkali are discussed. Special cases where these wavelengths coincide with strong resonance transitions in group-II atoms, Yb, Dy, Ho, and Er are identified. Measurements of the magic-zero wavelength points for benchmark tests of theory and experiment are proposed. [Preview Abstract] |
Wednesday, June 15, 2011 2:36PM - 2:48PM |
K7.00004: Spin-exchange collision cooling in an ultracold $^{85}$Rb/$^{87}$Rb Mixture Mathew Hamilton, Rebekah Ferrier, Jacob Roberts We have confined ultracold $^{85}$Rb and $^{87}$Rb simultaneously in an optical trap. Through optical pumping, spin-exchange collisions between $^{85}$Rb and $^{87}$Rb in a magnetic field can be made to be endothermic, transferring kinetic energy to Zeeman energy. Subsequent optical pumping removes the Zeeman energy from the gas, cooling it without requiring atom loss. We describe our implementation of this cooling scheme\footnote{G. Ferrari, European Physical Journal D 13, 67-70 (2001).} and describe our experimental observations and characterizations of this cooling. We also discuss the advantages of using two different types of atoms in the cooling. [Preview Abstract] |
Wednesday, June 15, 2011 2:48PM - 3:00PM |
K7.00005: Recent data on a new method for producing ultracold molecular ions Wade Rellergert, Scott Sullivan, Kuang Chen, Steven Schowalter, Eric Hudson We present recent data from our experimental effort to produce ultracold, internal ground-state BaCl$^{+}$ ions using a Ca MOT. The method utilizes sympathetic cooling due to the strong collisions between co-trapped molecular ions and laser-cooled neutral atoms which should efficiently cool both the internal and external molecular ion degrees of freedom. Samples of such ultracold molecular ions find applications in ultracold chemistry, precision measurement and quantum computation. [Preview Abstract] |
Wednesday, June 15, 2011 3:00PM - 3:12PM |
K7.00006: Internal state cooling using optical frequency combs in the presence of decoherence Svetlana Malinovskaya, Tom Collins We discuss a theory of internal state cooling of molecules from Feshbach states using optical frequency combs and taking into account decoherence. The technique makes use of multiple two-photon resonances induced by optical frequencies present in the comb. It provides us with a useful tool to study the details of molecular dynamics at ultracold temperatures. Particularly, we analyze the impact of spontaneous decay of intermediate, electronically excited states, and collisions that involve ultracold molecules and molecules in Feshbach state as well as in the excited states. We show that the interplay of the spontaneous decay rate and the collision rate may result in an increase of the quantum yield of ultracold molecules. The fact that an optical frequency comb may address several excited states having different decay rates and transition dipole moments justifies the viability of its implementation for molecular cooling. [Preview Abstract] |
Wednesday, June 15, 2011 3:12PM - 3:24PM |
K7.00007: Atom Trap Trace Analysis Reaches a Part-per-quadrillion Sensitivity Wei Jiang, William Williams, Kevin Bailey, Andrew Davis, Shuiming Hu, Zheng-Tian Lu, Thomas O'Connor, Roland Purtschert, Neil Sturchio, Yun Sun, Peter Mueller A quadrillion is 10$^{15}$. This is how many argon atoms one has to sift through in order to find just one atom of the radioactive isotope $^{39}$Ar. Atom Trap Trace Analysis (ATTA), a MOT-based atom counting method, is now able to unambiguously pick $^{39}$Ar out of a regular argon gas sample. The exceedingly rare $^{39}$Ar forms naturally in the environment by cosmic rays, decays with a half-life of 270 years, and is an ideal tracer to study ocean circulation or groundwater flow over the past few hundred years. In an ATTA apparatus, only $^{39}$Ar atoms are selectively captured by the MOT, appear as a bright dot, and can be counted one atom at a time using a sensitive camera. This work constitutes a major breakthrough in analytical capability, and promises to enable a wide range of applications in physics as well as earth sciences. [Preview Abstract] |
Wednesday, June 15, 2011 3:24PM - 3:36PM |
K7.00008: Anomalous diffusion of atoms in a 1D damped lattice Yoav Sagi, Miri Brook, Ido Almog, Nir Davidson We study experimentally the anomalous diffusion of atoms in one dimension. The ultra-cold atoms continuously scatter photons from a lattice which is in a configuration identical to the one used in the well-known Sisyphus cooling scheme. This produces a steady-state atomic velocity distribution which is a power law, with an exponent that depends on the lattice depth [1]. We image the atomic density distribution after a varying waiting time. The width of the atomic cloud exhibits a power law time dependence, and we extract its characteristic exponent for various lattice depths. We also show that the density distribution at different times is self-similar with the same characteristic exponent, in accordance with the predictions of a fractional diffusion equation [2]. \\[4pt] [1] P. Douglas, S. Bergamini, and F. Renzoni, Phys. Rev. Lett. 96, 110601 (2006). \newline [2] R. Metzler and J. Klafter, Physics Reports 339, 1 (2000). [Preview Abstract] |
Wednesday, June 15, 2011 3:36PM - 3:48PM |
K7.00009: Optimal trapping wavelengths of Cs$_2$ and RbCs molecules in an optical lattice Nadia Bouloufa, Olivier Dulieu, Romain Vexiau, Mireille Aymar, Johann Georg Danzl, Manfred J. Mark, Hans-Christoph N\"agerl The present work aims at finding optimal parameters for trapping of Cs$_2$ and RbCs molecules in optical lattices, with the perspective of creating a quantum degenerate gas of ground-state molecules. We have calculated dynamic polarizabilities of Cs$_2$ and RbCs molecules subject to an oscillating electric field, using accurate potential curves and electronic transition dipole moments. We show that for some particular wavelengths of the optical lattice, called ``magic wavelengths,'' the polarizability of the ground-state molecules is equal to the one of a Feshbach molecule. As the creation of the sample of ground-state molecules relies on an adiabatic population transfer from weakly-bound molecules created on a Feshbach resonance, such a coincidence ensures that both the initial and final states are favorably trapped by the lattice light, allowing optimized transfer in agreement with the experimental observation. [Preview Abstract] |
Wednesday, June 15, 2011 3:48PM - 4:00PM |
K7.00010: Enhanced MOT Atom Number via Zeeman-Shifted Bichromatic Cooling Eric Blanshan, Tara Cubel Liebisch, Elizabeth Donley, John Kitching A key issue in creating compact cold-atom samples for chip scale atomic devices is that the number of atoms captured in a magneto-optical trap (MOT) scales strongly with the laser beam diameter [Gibble et al., OL\textbf{17}, 526 (1992)]. To overcome this effect, we use bichromatic stimulated cooling [S\"{o}ding et al., PRL\textbf{78}, 1420 (1997)] to slow a Rb atomic beam and increase the atom number of a compact trap. By tuning the Rabi frequency and phase, trains of counter-propagating $\pi $-pulses are created which, with 4mW of total laser power, exert a cooling force 8x larger than the spontaneous limit. We broaden the velocity range addressed by the bichromatic light via the Zeeman shift from a magnetic field gradient which sweeps the bichromatic force profile from a higher velocity class down to our chosen center velocity, increasing the effective width of the profile by 50{\%}. We report that for effective cooling lengths under 4.5cm, greater MOT number enhancement occurs with swept stimulated forces than with spontaneous forces. This technique may be useful for producing cold atom samples for future compact technologies. [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