Proefschrift--Leyden. / "Samenvatting": p.[164]-169. Includes bibliographical references.

Thesis (Ph.D.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Joseph A. Shaw. Includes bibliographical references (leaves 191-198).

Thesis (M.S.)--University of Delaware, 2009. / Principal faculty advisor: Sandeep Patel, Dept. of Chemistry & Biochemistry. Includes bibliographical references.

Uma das propriedades fÃsicas mais utilizadas para a implementaÃÃo da tecnologia quÃntica à a polarizaÃÃo da luz. Entretanto, uma vez que a polarizaÃÃo da luz à frÃgil, à essencial que seja utilizado um sistema de correÃÃo de erro quÃntico a fim de tornar a informaÃÃo quÃntica viÃvel na polarizaÃÃo de um fÃton. Um mÃtodo de correÃÃo da polarizaÃÃo proposto para fÃtons isolados divide o canal em subcanais de tal forma que somente a variaÃÃo nesses subcanais destrÃi a informaÃÃo. Para isso, variaÃÃes rÃpidas devem acontecer no momento em que dois pulsos Ãpticos atravessam o subcanal. Neste trabalho analisa-se um modelo estatÃstico que usa o grau de despolarizaÃÃo da luz como uma probabilidade do subcanal sofrer pequenas variaÃÃes no perÃodo de tempo entre a passagem de dois pulsos. Para modelar as variaÃÃes dos parÃmetros do canal, utiliza-se o mÃtodo probabilÃstico de Poisson aplicado a eventos raros. Realiza-se uma estimativa usando mÃtodos numÃricos que mede o grau de polarizaÃÃo da luz para fazer uma previsÃo de como seria o comportamento na prÃtica do sistema de correÃÃo de erro quÃntico estudado. / One of the most used physical properties to implement quantum technology is the polarization of the light. However, since the polarization of the light is fragile, it is essential that a quantum error correction system is used to make quantum information feasible in the polarization of a photon. A method of correction of polarization proposed for isolated photons divides the channel into sub-channels in such a way that only the variation in those sub-channels destroys the information. Therefore, rapid changes must occur in the moment that two optical pulses pass through the sub-channel. This work analyses a statistical model that uses the degree of depolarization of the light as a probability for the sub-channel to undergo minute variations in the time between the passage of two pulses. To model the variations of the parameters of the channel, it is used the probabilistic method of Poisson, applied to rare events. An estimate can be done using numerical methods which measures the degree of polarization of the light to predict how would be the behavior in the practice of the quantum error correction system studied.

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The CLAS Collaboration is using the p(e, e′ K+ p)π- reaction to perform a measurement of the induced polarization of the electroproduced Λ(1116). The parity-violating weak decay of the Λ into pπ- (64%) allows extraction of the recoil polarization of the Λ. The present study uses the CEBAF Large Acceptance Spectrometer (CLAS) to detect the scattered electron, the kaon, and the decay proton. CLAS allows for a large kinematic acceptance in Q2 (0.8 ≤ Q2 ≤ 3.5 GeV2 ), W (1.6 ≤ W ≤ 3.0 GeV), as well as the kaon scattering angle. In this experiment a 5.499 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. The goal is to map out the kinematic dependencies for this polarization observable to provide new constraints for theoretical models of the electromagnetic production of kaon-hyperon final states. Along with previously published photo- and electroproduction cross sections and polarization observables from CLAS, SAPHIR, and GRAAL, these data are needed in a coupled-channel analysis to identify previously unobserved s-channel resonances.

In this thesis we describe the results of two sets of experiments on spin-polarized atomic hydrogen at temperatures below 1 K using a 115 GHz heterodyne ESR spectrometer. First, we have made measurements of the rates of the two-body recombination processes in spin-polarized atomic hydrogen gas and spin-polarized atomic deuterium gas in a 41 kG field. In the second set of experiments, we examined the ESR absorption line associated with the spin-polarized atomic hydrogen atoms adsorbed on surfaces of liquid helium. In hydrogen, a comparision of the measured recombination rates in 41 kG with the corresponding rates measured in different magnetic fields showed that an additional recombination process is activate for the conditions of these experiments. We demonstrate that this is due to a resonant recombination process via the (v,J) = (14,4) level of molecular hydrogen. In spin-polarized deuterium, we found that the recombination rate are much larger than the analogous rates in hydrogen, and therefore that atomic deuterium gas is much less stable than the hydrogen system under comparable conditions. We report the first observation and study of doubly spin-polarized deuterium, a gas in which both the deuteron and electron spins are aligned. At temperatures near 0.1 K, the absorption line of doubly spin-polarized H atoms changes drastically as a peak appears on both sides of the peak associated with the bulk atoms. We have shown that these new peaks are due to the atoms which are adsorbed onto the surface of the liquid helium film that coats the walls of the microwave cavity. The geometry dependent non-zero average magnetic dipolar field due to aligned spins on a planar surface results in a shift of the position of the ESR absorption lines. The lineshapes of the side peaks are very unusual and are best described as ramp-like. Even after extensive attempts to explain this lineshape, we still do not know what mechanism is responsible. / Science, Faculty of / Physics and Astronomy, Department of / Graduate