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 B2: Ultracold Molecules |
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Chair: Phil Gould, University of Connecticut Room: Imperial Center |
Wednesday, May 26, 2010 10:30AM - 10:42AM |
B2.00001: Efimov physics in 6Li atoms Daekyoung Kang, Eric Braaten, Hans-Werner Hammer, Lucas Platter A new narrow three-atom loss resonance associated with an Efimov trimer crossing the three-atom threshold has recently been discovered in a many-body system of ultracold 6Li atoms in the three lowest hyperfine spin states at a magnetic field near 895 G. O'Hara and coworkers have used measurements of the three-body recombination rate in this region to determine the complex three-body parameter associated with Efimov physics. Using this parameter as the input, we calculate the universal predictions for the spectrum of Efimov states and for the three-body recombination rate in the universal region above 600 G where all three scattering lengths are large. We predict an atom-dimer loss resonance at 672 $\pm$2 G associated with an Efimov trimer disappearing through an atom-dimer threshold. We also predict an interference minimum in the three-body recombination rate at 759 $\pm$1 G where the three-spin mixture may be sufficiently stable to allow experimental study of the many-body system. [Preview Abstract] |
Wednesday, May 26, 2010 10:42AM - 10:54AM |
B2.00002: Universality in weakly-bound bosonic clusters Javier von Stecher We study the behavior of weakly bound clusters and their relation to the well-known three-body Efimov states. We adopt a model to describe universal behavior of strongly interacting bosonic systems in the large scattering length regime. Combining numerical methods such as quantum Monte Carlo and correlated Gaussians, we obtain an accurate description of cluster states. For three- and four-body systems, we recover the universal predictions. Then, we extend our study to larger systems and identify a series of states that can be qualitatively interpreted as adding one particle at a time to an Efimov trimer. The properties of these cluster states and their experimental signatures are discussed. [Preview Abstract] |
Wednesday, May 26, 2010 10:54AM - 11:06AM |
B2.00003: Extending universal three-body physics to finite energies: Efimov features for $a<0 $ Yujun Wang, B.D. Esry We have identified universal features in the energy dependence of the three-body recombination rates for cold atoms. These features can be traced to Efimov physics and are modified near a narrow Feshbach resonance. In particular, these features, found when the scattering length is negative, are not changed by the higher partial wave contributions. We have systematically studied the Efimov features in heteronuclear three-body collisions and have identified systems and parameters that facilitate experimental observation of multiple Efimov features. We have also found that the thermal averaging necessary at temperatures above the ultracold regime has little effect on the energy-dependent features, which opens the opportunity to use the same kind of loss experiments that have been so successful in observing ultracold scattering length dependent Efimov features. [Preview Abstract] |
Wednesday, May 26, 2010 11:06AM - 11:18AM |
B2.00004: Recombination of Three Dipoles into Weakly Bound Dimers Seth Rittenhouse, Christopher Ticknor Three-body recombination has proven to be an important component in understanding the lifetime of ultra-cold atomic gases. Similarly, in the absence of two-body loss processes, recombination of three bosonic dipoles is the main pathway for loss in an ultracold gas of dipolar molecules. We present new results predicting universal behavior in this process for positive s-wave scattering length as well as the scaling behavior at large scattering length. Corrections due to the presence of the long-range anisotropic dipolar interaction are included. [Preview Abstract] |
Wednesday, May 26, 2010 11:18AM - 11:30AM |
B2.00005: Optical Feshbach Resonances in $^{88}$Sr Travis Nicholson, Sebastian Blatt, Benjamin Bloom, Jun Ye Recent proposals have shown that quantum degenerate gases of alkaline earth atoms can be used for a number of novel quantum computing and quantum simulation experiments [1]. Strontium seems to be a good candidate for such experiments because of the precise control and high-resolution spectroscopy demonstrated by optical lattice clocks [2]. Unfortunately, the small scattering length of $^{88}$Sr is not amenable to evaporative cooling techniques that are usually used to reach quantum degeneracy [3,4]. Furthermore, increasing the scattering length of alkaline earths with a magnetic Feshbach resonance is not possible due to their spinless electronic ground state configuration. However, recent theoretical and experimental work suggests the possibility of changing scattering lengths in alkaline earths with laser light [5]. Using this optical Feshbach resonance near strontium's narrow ${^{1}S_{0}} \rightarrow {^{3}P_{1}}$ intercombination transition might allow its scattering length to be controlled without significant atom loss. We report our progress in demonstrating an optical Feshbach resonance in $^{88}$Sr. \\{} [1] A.J. Daley et al., Phys. Rev. Lett. \textbf{101}, 170504 (2008) \\{} [2] G.K. Campbell et al., Science \textbf{324}, 360 (2009) \\{} [3] S. Stellmer et al., Phys. Rev. Lett. \textbf{103}, 200401 (2009) \\{} [4] Y.N. Martinez de Esobar et al., Phys. Rev. Lett. \textbf{103}, 200402 (2009) \\{} [5] T. Zelevinsky et al., Phys. Rev. Lett \textbf{96}, 203201 (2006) \\{} [Preview Abstract] |
Wednesday, May 26, 2010 11:30AM - 11:42AM |
B2.00006: Optical Feschbach Resonances Beyond the Single Bound-State Model Krittika Kanjilal, Iris Reichenbach, Ivan Deutsch Optical Feshbach resonances (OFR) provide the promise of control of interatomic cold collisions for species with no magnetically controlled resonances, such as Group-II elements, and have potential advantages such as rapid spatio-temporal variation. OFRs are, however, typically associated with large inelastic collisions due to absorption and decay. It has been proposed that the ${}^{1}S_{0} \rightarrow {}^{3}P_{1}$ intercombination line of Group-II elements are particularly suitable for optical Feshbach resonances (OFRs), but the appropriate regime of operation is still not clear. In the case that the laser frequency is detuned very far from resonance to reduce losses, the scattering state in the ground-electronic open channel couples to more than one bound state of the excited-electronic closed channel potential. So far theoretical treatments of Feshbach resonances have only considered a single excited bound state. We explore the effects of the multiple eigenstates of the closed channel potential on the scattering length and the loss rate. We study this using a toy model is based on a simplified coupled channels approach within a finite quantization volume. [Preview Abstract] |
Wednesday, May 26, 2010 11:42AM - 11:54AM |
B2.00007: Pulsed Laser Depletion Spectroscopy of Ultracold NaCs Molecules Patrick Zabawa, Amy Wakim, Amanda Neukirch, Nicholas Bigelow, Elena Pazyuk, Andrey Stolyarov, Maris Tamanis, Ruvin Ferber We have labeled several deeply bound vibrational quanta in the $X^1\Sigma ^+$ electronic state in a sample of ultracold NaCs ($\sim $200 $\mu $K). The molecules are prepared from Magneto-Optical Traps (MOTs) via photoassociation with a laser field detuned from the Cs $6^2S_{1/2} -6^2P_{3/2} $ transition. We illuminate the sample with a tunable depletion pulse from a pulsed dye laser $\sim $100 $\mu $s before a Resonance Enhanced Multi-Photon Ionization (REMPI) detection pulse. By leaving the REMPI pulse frequency fixed, and scanning the depletion pulse frequency, we observe the vibrational progression of the excited electronic state from a single ground vibrational level. This technique allows us to scan large portions of the spectrum ($\sim $30 nm for a single laser dye) very quickly and with great efficiency, though with lower resolution ($\sim $1 cm$^{-1})$ than the CW depletion method. With this technique we have also observed the dissociation limit of NaCs above the Cs $6^2P_{3/2} $asymptote, which allows an independent verification for binding energies. An analysis of these spectra indicates the presence of $X^1\Sigma ^+$ molecules in the $\nu $ = 4, 5, 6, 9, 10, 11, 19 vibrational states. [Preview Abstract] |
Wednesday, May 26, 2010 11:54AM - 12:06PM |
B2.00008: Spectroscopic analysis of the $\left( 2 \right)^3\Sigma ^+$ state of ${ }^{\mbox{41}}\mbox{K}{ }^{\mbox{87}}\mbox{Rb}$ towards ultracold rovibronic ground-state molecules Kiyotaka Aikawa, Jun Kobayashi, Masahito Ueda, Shin Inouye Optical transitions from loosely bound ${ }^{\mbox{41}}\mbox{K}{ }^{\mbox{87}}\mbox{Rb}$ molecules to the $\left( 2 \right)^3\Sigma ^+$ state were investigated to search for an optimal intermediate state in the STIRAP transfer into the rovibrational ground state. The loosely bound molecules were produced by photoassociation of laser-cooled ${ }^{\mbox{41}}\mbox{K}$ and ${ }^{\mbox{87}}\mbox{Rb}$ atoms and detected by resonance-enhanced multi-photon ionization. High-resolution depletion spectra were obtained by scanning Ti: Sapphire laser in the wavelength range 880-920nm where no information on the $\left( 2 \right)^3\Sigma ^+$ state was available. Vibrational progressions over 17 levels and rotational progressions of J = 0-5 ($\Omega =0)$ and J = 1-5 ($\Omega =1)$ were observed. Rotational constants extracted from the spectra show a wide variation among vibrational levels which indicates spin-orbit mixing of the $\left( 1 \right)^3\Pi $ state into the $\left( 2 \right)^3\Sigma ^+$ state. The observed small splitting in each rotational line was understood in terms of hyperfine interaction between the nuclear spin of ${ }^{\mbox{87}}\mbox{Rb}$and electronic spin. [Preview Abstract] |
Wednesday, May 26, 2010 12:06PM - 12:18PM |
B2.00009: Collision physics and collective phenomena with ultra-cold atoms and molecules Eite Tiesinga I will describe some of our recent results on collision physics and collective phenomena with ultra-cold atoms and molecules. In particular, we have investigated how radio-frequency radiation can induce new or modify existing Feshbach resonances [1], and how ultra-cold polar molecules, such as KRb, can be formed and themselves collide [2]. We have studied collective phenomena of ultra-cold atoms as well. In particular, we have investigated interference patterns generated by atoms suddenly loaded into an optical lattice [3], the effect of rotation on strongly-interacting fermionic atoms [4], and studied the loss of energy in a three-component spinor-condensate [5].\\[4pt] [1] A.M. Kaufman, R.P. Anderson, T.M. Hanna, {\it et al.}, Phys Rev. A {\bf 80}, 050701(2009)\\[0pt] [2] S. Kotochigova, E. Tiesinga, P.S. Julienne, New J. Phys {\bf 11}, 055043 (2009)\\[0pt] [3] P.R. Johnson, E. Tiesinga, J.V. Porto {\it et al.}, New J. Phys {\bf 11}, 093022 (2009)\\[0pt] [4] M. Iskin, E. Tiesinga, Phys Rev. A {\bf 79}, 053621 (2009)\\[0pt] Y. Liu, E. Gomez, S.E. Maxwell, {\it et al.}, Phys Rev. Lett. {\bf 102}, 225301 (2009) [Preview Abstract] |
Wednesday, May 26, 2010 12:18PM - 12:30PM |
B2.00010: Analysis of ultracold Rb + Yb collisions Stephen Maxwell, Eite Tiesinga, Paul Julienne We present predictions for s-wave scattering lengths and bound state energies for all 14 isotopic combinations of Rb and Yb. Groups at NIST/JQI (Porto \textit{et al.}) and in D\"{u}sseldorf (G\"{o}rlitz \textit{et al.}) are currently pursuing experiments using this system. The D\"{u}sseldorf group has recently observed phase separation at thermal temperatures of the co-trapped $^{87}$Rb + $^{174}$Yb system, indicating a very strong interaction. In contrast, they observed low thermalization rates in co-trapped $^{87}$Rb + $^{170}$Yb, indicating a very weak interaction. These two data points provide bounds on scattering lengths. The universal properties of van der Waals potentials, using our estimate of the C$_{6}$ coefficient, and mass scaling then allows a determination of the number of bound states in the potential, all s-wave scattering lengths, and energies of weakly-bound states. The calculated scattering lengths range from very large and positive to very large and negative, with every qualitatively different regime in-between represented. [Preview Abstract] |
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