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 K4: Atom Optics, Atom Interferometry, and Cavity QED |
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Chair: L. A. Orozco, University of Maryland Room: Burnham Yates Conference Center Hawthorne |
Friday, May 20, 2005 10:30AM - 10:42AM |
K4.00001: A Microchip Ring Trap for Cold Atoms Paul Baker, Matt Crookston, Mike Robinson We describe a method to create a circular magnetic waveguide for deBroglie waves on a microchip. The guide is a 2-dimensional magnetic minimum for trapping weak-field seeking states of atoms or molecules with a magnetic dipole moment. It is created completely by electric currents in wires that are lithographically patterned on a multi-level chip. We describe the geometry and time-dependent currents of the wires and show that it's possible to wrap the waveguide in a complete circle with minimal perturbations due to the leads or wire crossings. This maximal area geometry is suited for rotation sensing with atom interferometry via the Sagnac effect using either cold thermal atoms and molecules or Bose-condensed systems. [Preview Abstract] |
Friday, May 20, 2005 10:42AM - 10:54AM |
K4.00002: Reconstruction of the phase of matter-wave fields using nonlinear wave-mixing Dominic Meiser We investigate the prospects of a matter-wave version of the so-called FROG nonlinear autocorrelation technique for the recovery of amplitude and phase of the condensate wave function of a Bose-Einstein condensate. For more than a decade, this method has been used successfully for the measurement of the amplitude and phase of ultra-short laser pulses. Key features of the FROG technique are its high resolution, versatility and stability against noise and some sources of systematic errors. After showing how its analogue can be realized for Bose-Einstein condensates, we apply it to the measurement of the wave function of a vortex state. The impact of a reduction of the number of measurements and typical sources of noise on the field reconstruction are analyzed. [Preview Abstract] |
Friday, May 20, 2005 10:54AM - 11:06AM |
K4.00003: Nano-Fabricated Gratings for Electrons Glen Gronniger, Brett Barwick, Tim Savas, Herman Batelaan We explore the lower energy range for electron diffraction from a Au and Pd coated nano-fabricated transmission grating. This has the promise of providing a route to the lowest energy electron interferometer currently possible. Starting at 1000 eV we get well resolved diffraction peaks. As 60 eV electron energy is approached the diffraction peaks broaden to the extent that they are hard to resolve. We attribute this to an effective loss of transverse coherence length. We show that the broadening and coherence loss can be modeled with a path integral calculation where the essential ingredient is a random spatially varying potential with a typical length scale of 200 nm. The effect of other coatings, such as Ni, is investigated and indicates that lower electron energies can be reached. Work supported by NSF, DOD-EPSCoR. [Preview Abstract] |
Friday, May 20, 2005 11:06AM - 11:18AM |
K4.00004: A polarizing beam splitter for dipolar molecules Omjyoti Dutta, Markku J\"{a}\"{a}skel\"{a}inen, Pierre Meystre We analyze a coherent beam splitter for polarized heteronuclear molecules based on a STIRAP scheme that uses a tripod linkage of electro-translational molecular states. We show that for strongly polarized molecules the rotational dynamics imposes significantly larger Rabi frequencies than would be otherwise be expected, but within this limitation, a full transfer of the molecules to two counter propagating ground-state wave packets is possible. [Preview Abstract] |
Friday, May 20, 2005 11:18AM - 11:30AM |
K4.00005: Dynamics of Bose-Einstein condensates in double wells Markku J\"{a}\"{a}skel\"{a}inen, Pierre Meystre We study the dynamics of Bose-Einstein condensates in double- well potentials following a sudden change from close to the Mott insulator regime to the superfluid regime (for repulsive interactions) or from a superfluid to a superposition state (for attractive interactions). We study both the case of symmetric trapping potentials and the effects of an symmetry due to an external field. We visualize the dynamics of the system in phase space using a quasi-probability distribution that allows for an intuitive interpretation of the various types of ynamics. For repulsive two-body interactions the visibility of the interference fringes that result from the superposition of the two condensates following a stage of ballistic expansion exhibits a collapse of coherent oscillations onto a background value whose magnitude depends on the amount of squeezing of the initial state. Strong attractive interactions are found to stabilize the dynamics of the relative number dynamics in the two wells. [Preview Abstract] |
Friday, May 20, 2005 11:30AM - 11:42AM |
K4.00006: Light scattering to determine the relative phase of two Bose-Einstein Condensates M. Saba, T.A. Pasquini, C. Sanner, Y. Shin, G. Jo, W. Ketterle, D.E. Pritchard We demonstrate an experimental technique to continuously sample the relative phase of two spatially separated Bose-Einstein condensates of atoms. The technique is based on stimulated Bragg scattering of light and can measure the phase of two condensates that have never been in contact [1]. The phase measurement process itself created a relative phase between two condensates with no initial phase relation, read out the phase, and monitored the phase evolution. This technique has applications for the study of weakly coupled condensates, Josephson oscillations, coherent manipulation and control of atomic wavefunctions. We demonstrate its potential realizing a novel atom interferometer between two trapped Bose-Einstein condensates without need for splitting or recombining the atom cloud. [1] M. Saba, T. A. Pasquini, C. Sanner, Y. Shin, W. Ketterle, and D. E. Pritchard, Light scattering to determine the relative phase of two BoseEinstein Condensates, Science, in press (2005). [Preview Abstract] |
Friday, May 20, 2005 11:42AM - 11:54AM |
K4.00007: Atom trapping with a thin magnetic film Micah Boyd, Gretchen Campbell, Jonchul Mun, Erik W. Streed, Aaron E. Leanhardt, David E. Pritchard, Wolfgang Ketterle We have demonstrated trapping of neutral atoms using magnetic fields produced by a thin magnetic film. The film was magnetized in alternating north/south stripes with a 10 $\mu m$ period. The magnetizable surface used was a hard disk platter provided by Hitachi Global Storage Technologies. Tube shaped traps were created with an additional radial bias field, and the traps were loaded with atoms from a $^{87}$Rb BEC. Radial trap frequencies of up to 20 kHz were observed. Recent results may include imaging of the individual trap sites as well as experiments with the surface as an atomic mirror. [Preview Abstract] |
Friday, May 20, 2005 11:54AM - 12:06PM |
K4.00008: Many-body bound states in waveguide bends R Cabrera-Trujillo, B.D. Esry, M.W.J. Bromley It is well known that a particle can be bound in the bend of a waveguide. We will present the results of calculations exploring whether many particles can be similarly bound when the interparticle interactions are included in a mean field approximation. In particular, we calculate the maximum number of atoms that can be bound as a function of the scattering length for various bend parameters. Possible consequences for matter wave propagation through the bend will be discussed. [Preview Abstract] |
Friday, May 20, 2005 12:06PM - 12:18PM |
K4.00009: Interaction-induced loss of contrast in Michelson-type atom interferometers Maxim Olshanii, Vanja Dunjko We develop an analytic model able to quantitatively explain the degradation of contrast in the recent experiment with the Michelson interferometer on a chip (Y.-J. Wang et al, cond-mat/0407689). We show that the main source of degradation is the interaction-induced distortion of the interferometric path, while the first-order coherence does not play any role. The nonlinear WKB technique we introduce allows one to deduce that interaction between two atoms in opposite interferometer arms is effectively a factor of two stronger than the one within the same arm, due to an unexpected Fock correction. Our results stand in an excellent agreement with the experimental data. [Preview Abstract] |
Friday, May 20, 2005 12:18PM - 12:30PM |
K4.00010: Entanglement evolution in cavity QED. D.L. Freimund, M.L. Terraciano, R. Olson, L.A. Orozco, P.R. Rice, J. Gea-Banacloche We investigate the evolution of entanglement in a strongly coupled cavity QED optical system when the driving field is weak enough that the steady state value of the intracavity photon number is less than the saturation photon number. We use a cross correlation between the transmitted intensity and the fluorescence of the atoms into modes other than that of the cavity: $j^{(2)}(\tau) $ . We explore the parameter space, relevant for our current experiments, of the degree of entanglement as measured by $j^{(2)}(\tau)$. We find that it depends weakly on the number of atoms and the dipole coupling between the atom and the cavity; however we find that the degree of entanglement grows with the cavity linewidth and can reach an optimal value. We are currently characterizing a new cavity QED system and will report on our progress in the implementation of this cross-correlation function. This work is supported by NSF and NIST. [Preview Abstract] |
Friday, May 20, 2005 12:30PM - 12:42PM |
K4.00011: Experiments with ultracold atoms in an optical cavity Subhadeep Gupta, Kevin Moore, Kater Murch, Thomas Purdy, Dan Stamper-Kurn Magnetically-trapped ultracold atoms provide a robust, long-lived atomic source for many-atom cavity QED.~ We have developed a system which is capable of placing a large ensemble of Rb-87 atoms within the confines of a high finesse optical cavity.~ Recent experimental progress will be discussed. [Preview Abstract] |
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