Bulletin of the American Physical Society
38th Annual Meeting of the Division of Atomic, Molecular, and Optical Physics
Volume 52, Number 7
Tuesday–Saturday, June 5–9, 2007; Calgary, Alberta, Canada
Session P2: Rydberg Physics |
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Chair: B. Dunning, Rice University Room: TELUS Convention Centre Macleod C |
Friday, June 8, 2007 10:30AM - 11:06AM |
P2.00001: The Atomic Chameleons: Rydberg Wavepackets Invited Speaker: The ability to prepare Rydberg electrons in well-defined coherent superpositions and measure time-dependent changes in their quantum states allows one to take advantage of their exaggerated properties to explore a variety of phenomena. For example, we are currently using Rydberg wavepackets to investigate schemes for suppressing quantum decoherence in single-electron systems as well as for probing and controlling electron correlation in two-electron atoms. In the former case, we have successfully used time-dependent fields to decouple Rydberg atoms from a noisy environment, essentially eliminating wavepacket decoherence. In the latter experiments, we employ double Rydberg wavepackets to study controlled, strong-field, non-sequential double ionization in a previously unexplored regime. Specifically, we measure double ionization probability as a function of the energies and radial positions of two atomic electrons at the instant of their exposure to a strong, impulsive, half-cycle electric field. We are examining the possibilities for using double ionization as a probe of time-dependent electron correlation in these systems. [Preview Abstract] |
Friday, June 8, 2007 11:06AM - 11:42AM |
P2.00002: Rydberg excitation of cold atoms: dipole blockade and ionization. Invited Speaker: Cold Rydberg atoms are fascinating because they are at the frontier of atomic, solid state and plasma physics. Spectacular effects have their origin in the long-range dipole-dipole interactions between cold Rydberg atoms. In the presence of an electric field or at a F\"{o}rster resonance, the Rydberg excitation can be limited. Electric-field induced dipole blockade allows us to limit the excitation of p levels (principal quantum number n=80) up to 80 {\%} in a volume of typical dimension of 0.1 mm. The F\"{o}rster resonance configuration, for which Rydberg atoms exchange resonantly internal energy, is observed for n below 42 and leads to 30 {\%} efficiency in dipole blockade [T. Vogt \textit{et al.}, Phys. Rev. Lett. \underline {97}, 083003 (2006)]. Both experiments have permitted us to analyze the role of saturation and the role of the presence of one or a few spurious ions. The application of the dipole blockade effect in the realization of scalable quantum gates will be discussed. In a dense ensemble, cold Penning collisions between Rydberg atoms can be at the origin of an ionic space charge, important enough to then trap the electrons leading to the evolution towards an ultracold plasma formed in a ionization avalanche process. We demonstrate the possibility to control the mutual dipolar force between Rydberg atoms. [Preview Abstract] |
Friday, June 8, 2007 11:42AM - 12:18PM |
P2.00003: Rydberg atoms in Antihydrogen Experiments Invited Speaker: Recent experiments have observed the formation of antihydrogen atoms by mixing antiprotons and positrons. In most experimental configurations, the antihydrogen is formed through three body recombination while an antiproton traverses a cold positron plasma. These experiments take place with an unusual set of parameters. In particular, the atoms are formed in strong magnetic fields and the positron plasma is much colder than usual plasmas. The anti-atoms that are formed have some unexpected properties. In this talk, I will present the results simulations and measurements that give insight into the kinds of atoms that are formed. The focus will be on properties that might affect the chances of trapping these exotic atoms. [Preview Abstract] |
Friday, June 8, 2007 12:18PM - 12:54PM |
P2.00004: Forming, trapping, and cooling neutral antimatter: strongly magnetized highly excited antihydrogen atoms Invited Speaker: A theoretical framework for the formation of Rydberg atoms in strongly magnetized nonneutral plasma is described with an eye toward the production of highly excited Rydberg antihydrogen atoms at CERN. A number of challenges hindering a quantitative understanding of how Hbar atoms are formed- the details of velocity and field ionization spectra- are overcome. It is shown that a cooling technique due to spontaneous decay efficiently brings the Rydberg atoms to their ground state. The long-time dynamics in strong inhomogeneous magnetic field traps is numerically investigated using classical techniques, whereas the atomic state-specific structure is fully described quantum mechanically. Analytical expressions for the two limits of cooling- adiabatic and sudden cascades- as a function of trapping magnetic multipole order will be given. [Preview Abstract] |
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