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 E1: Rydberg Wavepackets and Ultra Cold Plasmas |
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Chair: Carlos Reinhold, Oak Ridge National Laboratory Room: Burnham Yates Conference Center Ballroom I |
Thursday, May 19, 2005 8:00AM - 8:36AM |
E1.00001: Tailoring Rydberg Wavepackets Invited Speaker: Advances in experimental technique now allow study of the behavior of Rydberg atoms subject to one, or more, pulsed unidirectional electric fields, termed half-cycle pulses (HCPs), whose duration is much less than the classical electron orbital period. In this limit, each HCP simply delivers an impulsive momentum transfer or ``kick" to the excited electron. The application of a carefully-tailored sequence of HCPs provides a powerful means to control and manipulate atomic wavefunctions. This task is greatly simplified if the initial wavefunction is first localised in phase space. This can be achieved by exciting quasi-one-dimensional (quasi-1D) Rydberg Stark states and applying a periodic train of HCPs. The phase space for such kicked atoms contains a series of stable islands embedded in a chaotic sea. Only that portion of the initial wavefunction positioned within a stable island survives leading to creation of a non-dispersive wavepacket that undergoes transient phase space localization and that can be steered toward different regions of phase space by ``chirping'' the frequency and/or amplitude of the HCP train. Application of a single HCP to a quasi-1D atom can also lead to strong transient phase space localization that can be trapped for extended periods using a train of subsequent HCPs. Once localized, further HCPs can be used to engineer a desired final state. For example, a HCP might be used to launch the electron into a near circular orbit or into a highly-elliptical orbit. Although this leads to population of a distribution of higher-n states, this distribution can be narrowed using additional HCPs. These approaches to atomic engineering will be discussed with the aid of recent results. [Preview Abstract] |
Thursday, May 19, 2005 8:36AM - 9:12AM |
E1.00002: Nondispersive wave packets -- control through chaos Invited Speaker: Nondispersive wave packets were predicted to emerge in periodically driven Rydberg atoms a little more than 10 years ago [1], and have now been observed in the laboratory [2]. I shall illustrate how these robust, generic ``quantum particles'' and their relatives naturally emerge from the theory of chaotic quantum systems [3], and thus open new perspectives for robust quantum control in various experimental settings -- from one and two-electron [4] atoms under periodic or impulsive [5] driving to cold atoms in flashing periodic potentials, possibly amended by harmonic confinement [6]. Besides the fundamental underlying (nonlinear) resonance phenomena also some more subtle properties will be discussed, including open questions within the realm of spectral theory. \begin{itemize} \item[1] A. Buchleitner, th\`ese de doctorat, Universit\'e Paris 6 (1993); I. Bialynicki-Birula, M. Kalinski, and J. H. Eberly, Phys. Rev. Lett. {\bf 73}, 1777 (1994); D. Delande and A. Buchleitner, Adv. At. Mol. Opt. Phys. {\bf 34}, 85 (1994). \item[2] H. Maeda and T. F. Gallagher, Phys. Rev. Lett. {\bf 92}, 133004 (2004). \item[3] A. Buchleitner, D. Delande, and J. Zakrzewski, Phys. Rep. {\bf 386}, 409 (2002). \item[4] J. Madro\~nero, PhD thesis, Ludwig-Maximilians-Universit\"at M\"unchen (2004), {\script http://edoc.ub.uni-muenchen.de/archive/00002187}. \item[5] D.G. Arb\'o et al., Phys. Rev. A {\bf 67}, 63401 (2003). \item[6] A.R.R. de Carvalho and A. Buchleitner, Phys. Rev. Lett. {\bf 93}, 204101 (2004). \end{itemize} [Preview Abstract] |
Thursday, May 19, 2005 9:12AM - 9:48AM |
E1.00003: Fluorescence Studies on Ultracold Plasmas Invited Speaker: Fluorescence studies of ultracold plasmas form a nice complement to recently-demonstrated ion absorption measurements. They offer some advantages in terms of both the signal-to-noise ratio, the ultimate sensitivity, and the fast time-scale of the response. In this talk I will present new fluorescence studies of ultracold plasmas and discuss their application to our understanding of the physics of strongly- coupled Coulomb systems. [Preview Abstract] |
Thursday, May 19, 2005 9:48AM - 10:24AM |
E1.00004: Collisions and interactions in ultracold Rydberg plasmas Invited Speaker: A new branch of atomic physics -~the interactions and collisions in ultracold Rydberg plasmas ($T\ll 1 K$) systems-~ has naturally evolved from recent advances in the cooling and trapping of neutral gases. Here we discuss the key collisional processes-- three-body recombination. electron-impact ionization of Rydberg atoms, radiative cascade of Rydberg atoms and Rydberg -Rydberg interactions --important to the evolution of the plasma. Quantal and classical radiative cascades are illustrated, together with the ``trajectory" in $n\ell$ space followed during the cascade. Theory and cross sections for ionization of Rydberg atoms in $n, \ell$ states by collision with electrons is presented. The full dependence of the cross sections on the initial angular momentum $\ell$ of the target is revealed, with interesting physical characteristics. Analytical curvefits for the cross sections are then provided so as to extract the rates for three-body capture into state $n,\ell$ from detailed balance. Three-body recombination followed by Stark mixing produce Rydberg atoms with a broad distribution of $\ell$ states. These states are sufficiently flexible that {\it permanent dipole} and higher {\it permanent multipoles} are created quite easily out of the large number $\sim n^2$ of degenerate angular momentum states $\ell$ within the energy shell. First-order interactions between Rydbergs therefore exist. We present the physics of the first-order long-range interaction between these polar Rydberg atoms and investigate the possible formation of long-range molecules from two Rydberg atoms with the same (or different) principal quantum numbers $n$, but with a broad superposition of many degenerate angular momentum states $\ell$. [Preview Abstract] |
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