Browsing by Author "Pu, Yu"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Effects of stray fields on ionization of Rydberg atoms near gold surfaces
    (2010) Pu, Yu; Dunning, F. B.
    The present work has explained a long-standing discrepency between theory and experiment: the broadening of the distances at which Rydberg atoms ionize over a metallic surface. The uneven surface potential distribution on a template-stripped gold surface evaporated on mica is measured with Kelvin probe force microscopy. The stray fields generated by the surface potential are calculated. Simulation with C++ and Matlab predicts how stray fields affect the ionization of Rydberg state atoms near a gold surface. The predicted survival probabilities for different n levels and different incident angles provided by the simulations are then compared with experiments, which shows surprisingly good agreement. Although metallic surfaces are approximately ideal equipotentials in the macroscopic world, Rydberg atoms demonstrate the important role stray fields play in the microscopic world.
  • Thumbnail Image
    Item
    Ionization of Rydberg Atoms at Patterned Electrode Arrays
    (2013-07-26) Pu, Yu; Dunning, F. B.; Killian, Thomas C.; McDevitt, John T.
    The present work explores the effect of controlled surface fields on the ionization of Rydberg atoms near surfaces. Lithographically-patterned micrometer scale electrode arrays are used to generate controlled surface electric fields. The data show that application of even small electrode biases (~±1V) can lead to a transition from ionization of the incident atoms by short-range tunneling to field ionization well above the target surface. The resulting ions are efficiently detected using ion collection fields whose strengths are substantially smaller than those required for direct field ionization implying the application of surface ionization in the detection of low-n Rydberg atoms. The data are analyzed with the aid of a Monte Carlo model and further demonstrate the critical role that local surface fields can play in governing the nature of atom-surface interactions.