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 N1: Thesis Prize Session |
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Chair: Steven Manson, Georgia State University Room: Knoxville Convention Center Lecture Hall |
Thursday, May 18, 2006 1:30PM - 2:06PM |
N1.00001: The Relative Phase of Two Spatially Separate Bose-Einstein Condensates Invited Speaker: Yong-Il Shin The relative phase of two Bose-Einstein condensates is a conclusive demonstration of the existence of phase coherence of Bose-Einstein condensates. Experimental control of the relative phase is an essential requirement for novel quantum applications using Bose-Einstein condensates, such as atom interferometry and quantum information processing. In this presentation, I describe our experimental works for studying coherent manipulation of the relative phase of two spatially separate condensates. We developed an optical double-well system having controllable well- separation and depth. Coherent dynamic splitting of trapped condensates was performed by deforming an optical single-well potential into a double-well potential. The relative phase of the two split condensates was shown to be reproducible and coherent phase evolution was observed for condensates held separated by 13 $\mu $m for up to 5 ms. We demonstrated trapped atom interferometry with this coherent beam splitter [1]. We developed an optical method for measuring the relative phase of two condensates. Coherent coupling between the two spatially separate condensates was established by using stimulated light scattering and the relative phase was continuously measured by monitoring the scattered photons. This continuous phase measurement presents a new type of atom interferometry without need for a conventional beam splitter or recombiner [2]. The Josephson-like phase dynamics of the coherent optical coupling was investigated and it was experimentally demonstrated that the induced atomic currents between the two condensates depend on the relative phase of the two condensates and an additional coupling phase which is experimentally controllable [3]. \newline [1] Y. Shin et al., Physical Review Letters \textbf {92}, 050405 (2004). \newline [2] M. Saba et al., Science \textbf{307}, 1945 (2005). \newline [3] Y. Shin et al., Physical Review Letters \textbf {95}, 170402 (2005). [Preview Abstract] |
Thursday, May 18, 2006 2:06PM - 2:42PM |
N1.00002: Fully Quantum Measurement of the Electron Magnetic Moment Invited Speaker: Brian Odom I report the first fully quantum measurement of the electron magnetic moment. This 0.6 parts per trillion result is the most accurate to date and is combined with existing Quantum Electrodynamics theory to yield a new value for the fine structure constant. The measurement uses quantum spectroscopy of transitions between the ground and first-excited cyclotron and spin states of a single electron, eliminating errors associated with relativistic mass corrections of excited states. A dilution refrigerator provides the 0.1 K temperature needed to cool the cyclotron motion, ensuring that only the ground state is occupied, and to cool the axial motion, reducing thermal broadening of the cyclotron and spin-flip resonances. The measurement is performed in a cylindrical trap cavity with well characterized electromagnetic standing-wave modes, making possible the first cavity-shift correction to the measured magnetic moment. [Preview Abstract] |
Thursday, May 18, 2006 2:42PM - 3:18PM |
N1.00003: Nonequilibrium Dynamics of Ultracold Neutral Plasmas Invited Speaker: Thomas Pohl Since their first creation by photoionization of laser-cooled neutral atoms, ultracold neutral plasmas (UNPs) are proving to be interesting dynamical systems on the border between atomic and plasma physics. The low initial temperatures suggest these systems to be in a strongly coupled state, where the electrostatic potential energy greatly exceeds the kinetic energy of the produced charges. Hence, they potentially allow to observe fundamental effects such as Coulomb crystallization in a two-component plasma or to study atomic collision processes under conditions, otherwise realized mostly in exotic astrophysical environments. I will present a numerical approach, which is demonstrated to yield an accurate description of recent experiments and to provide deeper insights into the complex system dynamics. Strong ion correlations are proven to profoundly affect the plasma evolution, leading, e.g., to a wave-like temperature dynamics as the system heats up intrinsically. It is found that common kinetic descriptions break down in this exotic regime, resulting in an unusual relaxation behavior towards thermodynamic equilibrium -- and even away from it. To get around the drawback of intrinsic plasma heating, I will discuss a promising perspective for controlling the degree of correlations in UNPs by laser-cooling the ions as the plasma expands. It turns out that additional cooling strongly modifies the plasma dynamics and allows for the realization of different phases. In fact, even Coulomb crystallization is shown to be achievable under realistic experimental conditions. Interestingly, the observed crystallization is found to proceed substantially different than the dynamical crystallization observed in ion traps. In this context, I will also discuss perspectives for trapping UNPs, including magnetic effects on several aspects of the system dynamics. [Preview Abstract] |
Thursday, May 18, 2006 3:18PM - 3:54PM |
N1.00004: Incoherent Waves and Random-Phase Solitons in Nonlinear Periodic Systems Invited Speaker: Oren Cohen The coherence of waves in periodic systems is crucial to their dynamics, as interference effects, such as Bragg reflections, largely determine their propagation. Most waves in nature, however, are only partially coherent, with fluctuations imparting a statistical character to their dynamics. While linear systems allow superposition, nonlinearity introduces a nontrivial interplay between the lattice structures, the coherence of the waves, and the nonlinearity. A major part of my doctoral research has been the theoretical and experimental study of the propagation of partially-incoherent light in nonlinear photonic lattices. Of particular importance was the prediction of incoherent lattice solitons, the characterization of their statistical properties and power spectra, and the first observation of random-phase solitons in nonlinear photonic crystals. My experiments in fact constitute the first observation of self-trapped incoherent wave-packets in any periodic system in nature. In addition, the experiments revealed that, under proper conditions, an incoherent beam with homogeneous \textbf{k}-space (momentum space) distribution can evolve into an incoherent lattice soliton. That is, during nonlinear propagation, there is a nontrivial energy transfer between the lattice modes. Further investigation of this energy-exchange led to the development of a new spectroscopy technique for periodic potentials, facilitating single-shot visualization of the extended Brillouin zones of the photonic lattice with the various bands and gaps, the spectrum of defects embedded in the lattice, and the regions of normal and anomalous diffraction. This research lays the foundation for all-optical studies of coherence dynamics that are universal to a variety of fields. Examples include photonic lattices, charge-density and spin waves in solids, phonons in biological molecules, and partially-condensed (finite-temperature) matter waves in periodic traps. [Preview Abstract] |
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