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Full-Text Articles in Physical Sciences and Mathematics

Two-Loop Bethe Logarithms For Higher Excited S Levels, Ulrich D. Jentschura Nov 2004

Two-Loop Bethe Logarithms For Higher Excited S Levels, Ulrich D. Jentschura

Physics Faculty Research & Creative Works

Processes mediated by two virtual low-energy photons contribute quite significantly to the energy of hydrogenic S states. The corresponding level shift is of the order of ( α / π )2 ( Z α )6 mec2 and may be ascribed to a two-loop generalization of the Bethe logarithm. For 1 S and 2 S states, the correction has recently been evaluated by Pachucki and Jentschura [Phys. Rev. Lett. 91, 113005 (2003)]. Here, we generalize the approach to higher excited S states, which in contrast to the 1 S and 2 S states can decay to …


Advances In Pattern Recognition Algorithms, Architectures, And Devices, Mohammad S. Alam, Mohammad A. Karim Jan 2004

Advances In Pattern Recognition Algorithms, Architectures, And Devices, Mohammad S. Alam, Mohammad A. Karim

Office of Research Faculty & Staff Publications

Over the last decade, tremendous advances have been made in the general area of pattern recognition techniques, devices, and algorithms. We have had the distinct pleasure of witnessing this remarkable growth as evidenced through their dissemination in the previous Optical Engineering special sections we have jointly edited— January 1998, March 1998, May 2000, and January 2002. Twenty-six papers were finally accepted for this latest special section, encompassing the recent trends and advancements made in many different areas of pattern recognition techniques utilizing algorithms, architectures, implementations, and devices. These techniques include matched spatial filter based recognition, hit-miss transforms, invariant pattern recognition, …


Quantum Lattice Representation Of Dark Solitons, George Vahala, Linda L. Vahala, Jeffrey Yepez Jan 2004

Quantum Lattice Representation Of Dark Solitons, George Vahala, Linda L. Vahala, Jeffrey Yepez

Electrical & Computer Engineering Faculty Publications

The nonlinear Schrodinger (NLS) equation in a self-defocusing Kerr medium supports dark solitons. Moreover the mean field description of a dilute Bose-Einstein condensate (BEC) is described by the Gross-Pitaevskii equation, which for a highly anisotropic (cigar-shaped) magnetic trap reduces to a one-dimensional (1D) cubic NLS in an external potential. A quantum lattice algorithm is developed for the dark solitons. Simulations are presented for both black (stationary) solitons as well as (moving) dark solitons. Collisions of dark solitons are compared with the exact analytic solutions and coupled dark-bright vector solitons are examined. The quantum algorithm requires 2 qubits per scalar field …