Bulletin of the American Physical Society
2006 37th Meeting of the Division of Atomic, Molecular and Optical Physics
Tuesday–Saturday, May 16–20, 2006; Knoxville, TN
Session L2: Undergraduate Research |
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Chair: Donald Griffin, Rollins College Room: Knoxville Convention Center Ballroom EFG |
Thursday, May 18, 2006 10:30AM - 10:50AM |
L2.00001: Experimental studies of laser light scattering in turbid media Sawyer Campbell, Rainer Grobe, Charles Su We inject an angularly collimated laser beam into a scattering medium of a non-dairy creamer-water solution and examine the distribution of the scattered light along the optical axis as a function of the source-detector spacing. The experimental and simulated data obtained from a Monte Carlo simulation on the optical axis suggest four regimes characterizing the transition from un-scattered to diffusive light. We compare the data with theoretical predictions based on a first-order scattering theory for regions close to the source, and with diffusion-like theories for larger source-detector spacings. We comment on the impact of the measurement on the light distribution and show that the regime of validity of these theories can depend on the experimental parameters such as the diameter and acceptance angle of the detection fiber. [Preview Abstract] |
Thursday, May 18, 2006 10:50AM - 11:10AM |
L2.00002: Macroscopic Quantum Tunneling and Entangled States in Bose-Einstein Condensates Dimitri Dounas-Frazer, Lincoln Carr We use a multi-band Bose-Hubbard model to study the quantum dynamics of ultracold bosons in a two-well potential. We describe the energy eigenstates in detail. These consist of oscillator-like solutions, non-degenerate entangled states, and degenerate entangled states which include extreme cat-states. The ground state ranges from a single number state to a coherent, or superfluid, state. In the dynamics we find harmonic breathing and quantum revivals. Finally, we describe the macroscopic quantum tunneling of a dark soliton between two wells. We show how the oscillation frequency depends on the band spacing and the ratio of the tunneling energy to the interaction potential. [Preview Abstract] |
Thursday, May 18, 2006 11:10AM - 11:30AM |
L2.00003: An imaging spectrometer to probe pondermotive-gradient field-ionization Jamie Kapplinger, Eric Wells A spectrometer has been developed with the capability to map Rydberg ions detected by a position-sensitive detector to their initial position within the focal volume of an intense laser pulse. This capability is key to constructing an experiment that can unambiguously verify the existence of the recently proposed pondermotive-gradient field-ionization mechanism.\footnote{E. Wells, I. Ben-Itzhak, and R.R. Jones, Phys. Rev. Lett.{\bf 93}, 023001 (2004)} To test the proposed spectrometer design, a simulation was developed to create an intensity-dependent population of Rydberg ions with a finite target temperature. This population was used as an input to the ion-optics simulation program. The simulated results indicate that the design provides sufficient resolution to indicate if the surviving Rydberg ions arise predominantly from the region of the focus with a relatively low pondermotive gradient [Preview Abstract] |
Thursday, May 18, 2006 11:30AM - 11:50AM |
L2.00004: Hertz level stabilization of a 657nm diode laser Brian Neyenhuis, Rebecca Tang, Greg Doermann, Dallin Durfee We will describe a 657nm diode laser locked to a high finesse cavity using the Pound-Drever-Hall method. This laser will be used to drive the calcium clock transition in a next generation atom interferometer. A new high speed lock circuit has been designed to increase the servo bandwidth and allow for straightforward optimization. An optimized scan balance is also included to allow the laser to be scanned over many GHz mode-hop-free. Locked to a cavity with a finesse of 30,000 a linewidth on the kHz level has been achieved. With further optimization, better passive stabilization, and the use of a 300,000 finesse cavity we hope to achieve a linewidth on the Hertz level in the near future. [Preview Abstract] |
Thursday, May 18, 2006 11:50AM - 12:10PM |
L2.00005: Two-stage Rydberg charge exchange in a strong magnetic field Michael Wall, Chris Norton, Francis Robicheaux We have performed calculations of two successive charge transfers from Rydberg states in a strong magnetic field. In the first charge transfer, a positron interacts with a highly excited atom to form positronium. In the second stage, the positronium interacts with a cold antiproton plasma to give anti-hydrogen. For many parameters, our results are in qualitative agreement with previous calculations with no magnetic field. However, we do find that there are important changes which may affect the usefulness of the method for efficient formation of anti-hydrogen that can be trapped. For example, some of the the positronium trajectories directly crossed magnetic field lines, whereas initial guesses would be that these light particles would remain fixed to them. Also, a large portion of the resulting anti-hydrogen was found to be in the high magnetic field seeking geometry, which would attract them to the walls of the trap. This causes them to annihilate and, subsequently, reduces the production rate. [Preview Abstract] |
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