Bulletin of the American Physical Society
2005 36th Meeting of the Division of Atomic, Molecular and Optical Physics
Tuesday–Saturday, May 17–21, 2005; Lincoln, Nebraska
Session J5: Bose Einstein Condensation II |
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Chair: Chris Greene, University of Colorado Room: Burnham Yates Conference Center Arbor |
Friday, May 20, 2005 8:00AM - 8:12AM |
J5.00001: Bose-Einstein condensation of interacting spin-1 $^{87}$Rb atoms in an all-optical trap M.-S. Chang, C.D. Hamley, Q. Qin, K.M. Fortier, M.S. Chapman Spinor condensates provide a weakly interacting, multi-component degenerate gas with rotational symmetry in spin space. Although the spin interactions are an order of magnitude weaker than the scalar mean-field density interaction, interesting spinor dynamics and novel phenomena can be observed, including multiple- condensation, spin mixing, and the formation of spin domains [1]. The spin interactions of $^87$Rb F=1 BEC are ferromagnetic in nature [2], and hence provide qualitatively different phenomena compared to anti-ferromagnetic ($^{23}$Na F=1) systems. We will discuss our recent experiment of $^87$Rb F=1 spinor condensates in a single-focused all-optical trap.\\ \\ 1. J. Stenger \textit{et al.}, Nature \textbf{396}, 345 (1998)\\ 2. H. Schmaljohann \textit{et al.}, Phys. Rev. Lett., \textbf {92}, 040402 (2004). M.-S. chang \textit{et al.}, Phys. Rev. lett., \textbf{92}, 140403 (2004). [Preview Abstract] |
Friday, May 20, 2005 8:12AM - 8:24AM |
J5.00002: Dynamical Instability of a Doubly Quantized Vortex in a Bose-Einstein Condensate Yong-il Shin, Michele Saba, Mukund Vengalattore, Thomas Pasquini, Christian Sanner, Aaron Leanhardt, Mara Prentiss, David Pritchard, Wolfgang Ketterle Doubly quantized vortices were topologically imprinted in sodium condensates [1], and their time evolution was observed using a tomographical imaging technique. The dynamical instability of a doubly quantized vortex state in a condesate was directly confirmed by observing that a doulby quantized vortex core split into two singly quantized vortex cores [2]. The characteristic time scale of the splitting process was found to be longer at higher atom density. [1] A.E. Leanhardt, et.al., Phys. Rev. Lett. 89, 190403 (2002). [2] Y. Shin, et.al., Phys. Rev. Lett. 93, 160406 (2004). [Preview Abstract] |
Friday, May 20, 2005 8:24AM - 8:36AM |
J5.00003: Temperature-dependent study of Bose gases : Crossover from three- to one-dimensional behavior Kwangsik Nho, Doerte Blume Using the finite-temperature path integral Monte Carlo method, we investigate the crossover of Bose gases from three- to one-dimensional behavior by incresing the trap anisotropy. The interaction between particles is modeled by hardcore potential with $s$-wave scattering length $a_{sc}$. Specifically, we monitor the energetics, the superfluid fraction, and structural properties as a function of temperature $T$, scattering length $a_{sc}$, and the trap anisotropy parameter. [Preview Abstract] |
Friday, May 20, 2005 8:36AM - 8:48AM |
J5.00004: Formation of molecules from a Cs Bose-Einstein condensate Vladimir Yurovsky, Abraham Ben-Reuven An analysis was carried out of the recent Innsbruck experiments [1] on the conversion to molecules of an expanding Bose-Einstein condensate of Cs atoms, using an extremely weak Feshbach resonance. The theory, based on the approach of [2], takes into account atom-molecule and molecule-molecule deactivating collisions. It describes results observed for both ramping and switching schemes used in the experiments, including the exceptionally effective conversion achieved in the switching scheme. A fit of the theory to the experimental data provides an estimate of the resonance strength and the deactivation rates. \newline \newline 1. M. Mark, T. Kraemer, J. Herbig, C. Chin, H.-C. N\"agerl, and R. Grimm, cond-mat/0409737. \newline 2. V. A. Yurovsky and A. Ben-Reuven, Phys. Rev. A {\bf 70}, 013613 (2004). [Preview Abstract] |
Friday, May 20, 2005 8:48AM - 9:00AM |
J5.00005: Progress Towards a 1-second BEC Interferometer Jessica Reeves, Cass Sackett, G. Ofir Garcia, Benjamin Deissler, Kenneth Baranowski, K. Jeramy Hughes, Patipan Uttayarat We have built a novel trap for creation of a Bose-Einstein condensate of $^{87}$Rb to be used in atom interferometry experiments. The trap is based on a time-orbiting potential waveguide. It supports the atoms against gravity while providing weak confinement to minimize interaction energy shifts. The waveguide is suitable for use in a wide variety of interferometer configurations. We anticipate long interactions times, of up to 1s, due to the low-noise features of the TOP trap. In particular, the atoms are held 5mm from any surface, minimizing any possible atom-surface effects. The resultant condensate interferometer will be useful in precision gravitation and rotation measurements. [Preview Abstract] |
Friday, May 20, 2005 9:00AM - 9:12AM |
J5.00006: BEC in a novel magnetic trap for many-atom cavity QED Kater Murch, Thomas Purdy, Kevin Moore, Subhadeep Gupta, Dan Stamper-Kurn We have produced a Rb-87 BEC in novel mm-scale Ioffe-Pritchard trap. The trap is designed to interface with a high finesse optical cavity with the goal of performing cavity QED with ultracold atomic samples. Performance of the trap and recent experimental progress will be discussed. [Preview Abstract] |
Friday, May 20, 2005 9:12AM - 9:24AM |
J5.00007: Nucleation and growth of vortical Wigner molecules in a rotating BEC. Oleg Vorov, Piet Van Isacker, Mahir Hussein, Klaus Bartschat An analytic expression for the ground-state wavefunction of a rotating Gross-Pitaevskii condensate of trapped atoms describes the onset of vorticity in an accelerated trap, starting from the vortex entry followed by formation of growing symmetric Wigner molecules [1]. Within a unified picture, it explains the staircase of the angular momentum jumps and the behavior of the bosonic occupancies observed in numerical and variational studies \hbox{[2-4]}. The similarity of this behavior and mesoscopic superconductors is discussed. \par\noindent [1] O.K. Vorov, P. Van Isacker, M.S. Hussein and K. Bartschat, submitted to Phys. Rev. Lett. (2005). \par\noindent [2] D.A. Butts and D.S. Rokhsar, Nature {\bf 397}, 327 (1999). \par\noindent [3] G.M. Kavoulakis, B. Mottelson, and C.J. Pethick, Phys. Rev. A {\bf 62}, 063605 (2000). \par\noindent [4] X.J. Liu, H. Hu, L. Chang, W. Zhang, S.Q. Li, and Y.Z. Wang, Phys. Rev. Lett. {\bf 87}, 030404 (2001). [Preview Abstract] |
Friday, May 20, 2005 9:24AM - 9:36AM |
J5.00008: Ring Dark Solitons in Bose-Einstein Condensates Bryan Nelsen, Mark Edwards, Lincoln Carr, Charles W. Clark The time-independent Gross--Pitaevskii equation describing a Bose--Einstein condensate confined in a cylindrical box admits ``ring solutions.''$^{1}$ These solutions consist of a central vortex line surrounded by concentric nodal rings. We have studied the time evolution of the ring solutions having one node between the vortex line at $\rho = 0$ and the box wall and which have had a phase mask placed across the node. This phase gradient mimics the phase jump exhibited by a dark soliton in motion. Our study has been carried out by solving the time--dependent Gross--Pitaevskii equation using a Crank--Nicolson propagator. The initial conditions were generated using a shooting algorithm that needed a power series solution of the time--indepedent Gross--Pitaevskii equation to find the solution away from the singularity at the vortex line. We find that, in general, these systems behave like dark or gray solitons where the node exhibits radial oscillations. We shall present results for various phase gradients and winding numbers and comment on the possibility of observing these phemomena in laboratory Bose--Einstein condensates.\\ \ \\ $^{1}$L.D.\ Carr and C.W.\ Clark, cond--mat/0408460 [Preview Abstract] |
Friday, May 20, 2005 9:36AM - 9:48AM |
J5.00009: Direct, Non-Destructive Imaging of Transverse and Longitudinal Magnetization in a Spin-1 Bose Gas Lorraine Sadler, James Higbie, Shin Inouye, Ananth Chikkatur, Sabrina Leslie, Kevin Moore, Veronique Savalli, Dan Stamper-Kurn Polarization-dependent phase contrast imaging is used to image the magnetization of an optically trapped ultracold gas in- situ, nondestructively, and repeatedly. This novel probe is applied to obtain time-resolved images of the Larmor precession of a spin-1 $^{87}$Rb Bose-Einstein condensate. The transverse magnetization of the condensate remains consistent with a mean- field model of interatomic interactions. Implications for precise magnetometry with high spatial resolution are discussed. [Preview Abstract] |
Friday, May 20, 2005 9:48AM - 10:00AM |
J5.00010: Quantum reflection at normal incidence Thomas Pasquini, Yong-Il Shin, Michele Saba, Gyu-Boong Jo, David Pritchard, Wolfgang Ketterle Quantum reflection occurs when an atom reflects from an attractive potential without reaching a classical turning point. Atoms will exhibit quantum reflection from the Casimir-Polder potential of a solid surface at sufficiently low incident velocity. Trapped Bose-Einstein condensates of $^{23}$Na, with peak density $10^{11}-10^{12}$~atoms/cm$^3$, normally incident on a silicon surface exhibited reflectivity of up to $20\%$ for incident velocities of $1-8$~mm/s. We discuss evidence for collective effects when a Bose-Einstein condensate undergoes quantum reflection, the possibility of confining atoms with solid surfaces, and recent experimental results. [Preview Abstract] |
Friday, May 20, 2005 10:00AM - 10:12AM |
J5.00011: Berry Phase in Semiclassical Dynamics of Bogoliubov Quasiparticles Chuanwei Zhang, Artem Dudarev, Qian Niu We develop a semiclassical theory for Bogoliubov waves by following the motion of wave-packets in real and momentum spaces. Because of the interaction between atoms, the semiclassical dynamics of Bogoliubov quasiparticles are found to be modified by the Berry phase and are very different from single particle excitations in a noninteracting system. We use this semiclassical approach to study the scattering of phonons by a vortex in a superfluid and calculate the transverse as well as longitudinal forces on the vortex. [Preview Abstract] |
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