Bulletin of the American Physical Society
43rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 57, Number 5
Monday–Friday, June 4–8, 2012; Orange County, California
Session H1: Focus Session: Efimov Physics in Cold Atoms |
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Chair: Cheng Chin, University of Chicago Room: Grand Ballroom BCD |
Wednesday, June 6, 2012 10:30AM - 11:00AM |
H1.00001: Universality of the Three-Body Parameter for Efimov States in Ultracold Cesium Invited Speaker: Rudolf Grimm We review recent progress in our understanding of universal few-body physics, considering the particular example of ultracold cesium gases with widely tunable s-wave interactions. We discuss the question of the so-called three-body parameter, which together with Efimov's famous scaling law fixes the values of the scattering length where three-body recombination resonances occur. A collection of experimental results on Cs and other species and recent theoretical results show a new type of universality for atomic systems, which connects the three-body parameter to the length scale introduced by the van der Waals interaction. Further progress has also been made regarding the generalization of Efimov's scenario to universal few-body cluster states. We report on the first observation of a five-body recombination resonance, which strongly supports the theoretical predictions on the existence of a universal series of N-body states. Moreover, we present new experimental results on modifications of Efimov physics in the dimensional crossover when the 3D confinement is changed into a 2D one. [Preview Abstract] |
Wednesday, June 6, 2012 11:00AM - 11:30AM |
H1.00002: Few-body physics for bosonic and fermionic dipoles Invited Speaker: Yujun Wang This invited talk, coauthored by Jose D'Incao and Chris Greene, will review our theoretical evidence that predicts an Efimov effect for three interacting bosonic polar molecules. Interestingly, the hyperspherical coordinate treatment shows a universal barrier which implies that the three-body parameter is rather accurately known in terms of the dipole length. It was not a foregone conclusion that three bosonic dipoles would exhibit Efimov physics, given that the original derivation and also subsequent work was for systems with short-range interactions only, and moreover, for systems having conserved angular momentum. Despite the fact that neither of these properties holds for three bosonic dipoles oriented in an external electric field, Efimov physics emerges naturally. For three fermionic dipoles in the same spin substate, on the other hand, there is no Efimov effect, but there is a single universal bound (or quasi-bound) state predicted to occur. Conditions under which these novel 3-dipole states could be observed experimentally will be discussed at the meeting. [Preview Abstract] |
Wednesday, June 6, 2012 11:30AM - 11:42AM |
H1.00003: Crossover between universal trimers and Efimov trimers Shimpei Endo, Pascal Naidon, Masahito Ueda For a system of two identical fermions and one distinguishable particle interacting via a short-range potential with a large $s$-wave scattering length, Efimov trimers [1] and universal trimers [2] exist in different regimes of mass ratio. These trimers have different scaling symmetry: discrete and continuous scaling symmetry. We point out the existence of a third kind of trimers, ``crossover trimers,'' that continuously connect the two regimes as the mass ratio and the scattering length are varied.\\[4pt] [1] V. Efimov, Nucl. Phys. A {\bf 210}, 157 (1973). \\[0pt] [2] O. I. Kartavtsev, and A. V. Malykh, J. Phys. B, {\bf 40}, 1429 (2007). [Preview Abstract] |
Wednesday, June 6, 2012 11:42AM - 11:54AM |
H1.00004: Efimov physics in a mixture of $^{40}$K and $^{87}$Rb Tyler Cumby, Ruth Shewmon, Ming-Guang Hu, Deborah Jin Three-body Efimov resonances have now been detected in a number of ultracold atom species using measurements of three-body recombination rates. Moreover, recent observations suggest that the locations of these resonances has some universality, in that they can be predicted using the two-body van der Waals length [1]. To compare with a recent prediction for the $^{40}$K + $^{87}$Rb system [2] and with a previous experimental result for $^{41}$K + $^{87}$Rb [3], we measure three-body recombination and molecule loss rates in an ultracold trapped gas of $^{40}$K and $^{87}$Rb atoms near an interspecies Feshbach resonance. \\[4pt] [1] PRL 107, 120401 (2011)\\[0pt] [2] arXiv:1111.1484v1\\[0pt] [3] PRL 103, 043201 (2009) [Preview Abstract] |
Wednesday, June 6, 2012 11:54AM - 12:06PM |
H1.00005: Origin of the Three-body Parameter Universality in Efimov Physics Jia Wang, J.P. D'Incao, B.D. Esry, Chris H. Greene One of the most fundamental theoretical assumptions concerning Efimov physics is that the three-body parameter depends on the precise details of the short-range two- and three-body interactions, i.e., it is not a universal parameter. Surprisingly, and contrary to this assumption, recent experiments exploring Efimov physics in ultracold quantum gases have found that the three-body parameter is universal. The present study investigates the origin of the universality of the three-body parameter in identical bosonic systems using the adiabatic hyperspherical representation. Our study shows that the universality of the three-body parameter emerges because a universal effective barrier in the important three-body potential prevents the three particles from simultaneously getting close to each other. Our results also set limits on this universality, showing it to be more likely to occur for neutral atoms and less likely to extend to light nuclei. [Preview Abstract] |
Wednesday, June 6, 2012 12:06PM - 12:18PM |
H1.00006: Universal three-body parameters in heteronuclear atomic systems Yujun Wang, Jia Wang, Jose D'Incao, Chris Greene Following the recent experimental and theoretical identifications of a universal three-body parameter in ultracold bosonic gases, we have calculated three-body parameters in heteronuclear three-atom systems near Feshbach resonances between distinguishable atoms. It is found that the three-body parameters, or the ground Efimov state energies, are universally determined by a combination of the long-range van der Waals interactions and the homonuclear scattering length. The positions of all the Efimov features in three-atom scattering processes in these heteronuclear systems can therefore be uniquely known. We show three-body parameters for some combinations of commonly-used alkali atoms in ultracold experiments with a wide range of homonuclear scattering lengths, and give an intuitive picture for understanding the universality in the Born-Oppenheimer limit where one of the atoms is much lighter than the others. Such knowledge of three-body parameters can be conveniently used to precisely calibrate the positions of the magnetic Feshbach resonances in ultracold experiments. [Preview Abstract] |
Wednesday, June 6, 2012 12:18PM - 12:30PM |
H1.00007: A new class of three-body states beyond the Efimov effect Nicolais L. Guevara, Brett D. Esry Recently, we have identified a new type of three-body bound state for three identical bosons interacting via attractive two-body $1/r^2$ potentials [1]. These three-body states are bound even when the two-body subsystem does not support a dimer state. In fact, there are an infinity of such states. We will present an extension of this work to the system with two identical bosons ($B$) and one distinguishable particle ($X$). We have investigated the spectrum of this $BBX$ system assuming only that the $B+X$ interaction is an attractive $1/r^{2}$ potential. We have again found an infinite number of three-body bound states even though the two-body potential does not support a bound state. This effect is shown to exist at large mass ratios ($M_B/M_X$) and depends on the strength of the two-body interaction. The most favorable case is the molecular-type system, i.e., $M_B/M_X \gg 1$. While these new three-body states resemble Efimov states they originate from fundamentally different physics.\\[4pt] [1] N. L. Guevara, Yujun Wang, and B. D. Esry, arXiv:1110.0476 (2011) [Preview Abstract] |
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