Quantum Markov Process on a Lattice

We develop a systematic description of Weyl and Fano operators on a lattice phase space. Introducing the so-called ghost variable even on an odd lattice, odd and even lattices can be treated in a symmetric way. The Wigner function is defined using these operators on the quantum phase space, which can be interpreted as a spin phase space. If we extend the space with a dichotomic variable, a positive distribution function can be defined on the new space. It is shown that there exits a quantum Markov process on the extended space which describes the time evolution of the distribution function.Comment: Lattice2003(theory

Quadratic cavity soliton optical frequency combs

We theoretically investigate the formation of frequency combs in a dispersive second-harmonic generation cavity system, and predict the existence of quadratic cavity solitons in the absence of a temporal walk-off

From weak to strong coupling of localized surface plasmons to guided modes in a luminescent slab

We investigate a periodic array of aluminum nanoantennas embedded in a light-emitting slab waveguide. By varying the waveguide thickness we demonstrate the transition from weak to strong coupling between localized surface plasmons in the nanoantennas and refractive index guided modes in the waveguide. We experimentally observe a non-trivial relationship between extinction and emission dispersion diagrams across the weak to strong coupling transition. These results have implications for a broad class of photonic structures where sources are embedded within coupled resonators. For nanoantenna arrays, strong vs. weak coupling leads to drastic modifications of radiation patterns without modifying the nanoantennas themselves, thereby representing an unprecedented design strategy for nanoscale light sources

Medida de la eficacia de dos hidrofugantes aplicados a rocas graníticas

We evaluated the efficacy of two water-repellents applied to three types of granitic rock widely used in building construction and restoration in Galicia (NW Spain). The depth of penetration of the water-repellents was determined by measuring capillary absorption by the treated rock. The efficacies of the water-repellent were evaluated in terms of two parameters characteristic of surface wet: water-rock contact angle and the time taken for absorption of microgroplets. The effects of the treatments on the rocks' surface color and permeability to water vapor were also determined. The results indicate that neither water-repellent effectively penetrates the rock surface, and both induce undesirably high reductions in vapor permeability. Notwithstanding, both agents effectively improved the rocks' resistance to surface wetting, without altering its surface color. Overall, determination of water-rock contact angle and the time taken for absorption of microdroplets, together with colorimetric characterization of the treated rock, constitutes an useful approach to evaluation of the effects of water-repellents on granitic rocks. Nonetheless, it should be borne in mind that the marked heterogeneity of this type of rock, and the associated mineralogy and dominant type of fissuration are sources of considerable variation in the measurement parameters.Se presentan los resultados de la aplicación de dos tratamientos hidrofugantes a tres rocas graníticas ampliamente utilizadas en la construcción y restauración en Galicia. Se ha determinado la profundidad de penetración de los hidrofugantes a través de la absorción capilar, la eficacia de los tratamientos comparando dos parámetros relacionados con el mojado superficial (ángulo de contacto roca-agua y tiempo de absorción de microgotas), y las variaciones en el color y en la permeabilidad al vapor. Se comprueba que si bien ambos tratamientos penetran deforma muy escasa en las rocas graníticas y reducen significativamente la permeabilidad al vapor, mejoran sensiblemente su comportamiento frente al mojado superficial sin modificar el color original. El ángulo de contacto, el tiempo de absorción de microgotas y la determinación colorimétrica utilizada, constituyen una buena metodología en la evaluación de los efectos de tratamientos hidrofugantes en rocas graníticas; sin embargo, el fuerte carácter heterogéneo este tipo de rocas, la mineralogía y el tipo de fisuración predominante, suponen un factor de variación significativo en la determinación de estos parámetros

Medida de la durabilidad de dos tratamientos de hidrofugación aplicados a rocas graníticas

The durability of two water-repellents for granitic stonework was determined. Weathered and sound samples of granites widely used in building construction and restoration in Galicia (NW Spain) were treated with water repellents of known efficacy, and then subjected to two artificial weathering tests: prolonged exposure to UV light, and sodium sulphate crystallization cycles. In both tests, but especially in the salt crystallization cycles, both treatments rapidly lost their water-repellency. Furthermore, the hydrophobic layer of water repellent impeded salt mobility, favouring fissuration parallel to the treated surface, which was eventually shed in the form of a plaque.Se presentan los resultados de la durabilidad de dos tratamientos de hidrofugación aplicados a rocas graníticas ampliamente utilizados en la construcción de edificios en Galicia (Noroeste de España). Tras la evaluación de la eficacia de dichos tratamientos, cuyos resultados se presentaron en un trabajo anterior, se someten las muestras tratadas a dos ensayos diferentes de envejecimiento acelerado: ciclos de exposición a la luz ultravioleta y ciclos de cristalización de sulfato de sodio. Los productos hidrofugantes muestran una escasa resistencia a ambos ensayos, sobre todo a los ciclos de cristalización de sulfato de sodio; esta débil durabilidad se manifiesta en una rápida pérdida de sus propiedades hidrofugantes. Así mismo, se observa que la presencia de la capa hidrófoba en la piedra funciona como una barrera frente a la movilidad de sales, lo que ocasiona el total desprendimiento de aquella y un fuerte deterioro del material rocoso