Tunable entanglement distillation of spatially correlated down-converted photons

We report on a new technique for entanglement distillation of the bipartite continuous variable state of spatially correlated photons generated in the spontaneous parametric down-conversion process (SPDC), where tunable non-Gaussian operations are implemented and the post-processed entanglement is certified in real-time using a single-photon sensitive electron multiplying CCD (EMCCD) camera. The local operations are performed using non-Gaussian filters modulated into a programmable spatial light modulator and, by using the EMCCD camera for actively recording the probability distributions of the twin-photons, one has fine control of the Schmidt number of the distilled state. We show that even simple non-Gaussian filters can be finely tuned to a ~67% net gain of the initial entanglement generated in the SPDC process.Comment: 12 pages, 6 figure

Analysing and controlling the tax evasion dynamics via majority-vote model

Within the context of agent-based Monte-Carlo simulations, we study the well-known majority-vote model (MVM) with noise applied to tax evasion on simple square lattices, Voronoi-Delaunay random lattices, Barabasi-Albert networks, and Erd\"os-R\'enyi random graphs. In the order to analyse and to control the fluctuations for tax evasion in the economics model proposed by Zaklan, MVM is applied in the neighborhod of the noise critical $q_{c}$. The Zaklan model had been studied recently using the equilibrium Ising model. Here we show that the Zaklan model is robust and can be reproduced also through the nonequilibrium MVM on various topologies.Comment: 18 pages, 7 figures, LAWNP'09, 200

Caracterização química e granulométrica de solos da baixada maranhense.

A área de estudo corresponde aos campos flúvio-marinhos com risco de inundação e presença de solos hidromórficos da região conhecida com Baixada e Golfão Maranhenses. os solos dessa região, por apresentarem drenagem com alguns impedimento e condições favoráveis a inundação, ficam sujeitos aos processos de evaporação, o que associado a proximidade do mar, pode elevar as concentrações de sais solúveis e inviabilizar ao reduzir a produção. Foram coletadas 38 amostras de terra em 22 pontos com trado holandês a profundidades variáveis, normalmente de 0 a 20 e de 30 a 50 cm de profundidade. A análise da terra fina seca ao ar (TFSA) permitiu a determinação de atributos químicos e granulométricos dos solos. Na região predominam solos com argila de atividade alta, relativamente ácidos e com elevados teores de bases e também de hidrogênio e alumínio, ocorrendo solos com caráter alumínico. Os teores de magnésio são predominantes em relação aos de cálcio. Apesar dos elevado grau de floculação. predominam solos de textura argilosa, porém ocorrem solos de textura arenosa, média e siltosa. Na fração área predomina a areia fina. Foram verificadas várias correlações entre os atributos dos solos

Spin-polarized transport in ferromagnetic multilayered semiconductor nanostructures

The occurrence of inhomogeneous spin-density distribution in multilayered ferromagnetic diluted magnetic semiconductor nanostructures leads to strong dependence of the spin-polarized transport properties on these systems. The spin-dependent mobility, conductivity and resistivity in (Ga,Mn)As/GaAs,(Ga,Mn)N/GaN, and (Si,Mn)/Si multilayers are calculated as a function of temperature, scaled by the average magnetization of the diluted magnetic semiconductor layers. An increase of the resistivity near the transition temperature is obtained. We observed that the spin-polarized transport properties changes strongly among the three materials.Comment: 3 pages, 4 figure

Bound vortex states and exotic lattices in multi-component Bose-Einstein condensates: The role of vortex-vortex interaction

We numerically study the vortex-vortex interaction in multi-component homogeneous Bose-Einstein condensates within the realm of the Gross-Pitaevskii theory. We provide strong evidences that pairwise vortex interaction captures the underlying mechanisms which determine the geometric configuration of the vortices, such as different lattices in many-vortex states, as well as the bound vortex states with two (dimer) or three (trimer) vortices. Specifically, we discuss and apply our theoretical approach to investigate intra- and inter-component vortex-vortex interactions in two- and three-component Bose-Einstein condensates, thereby shedding light on the formation of the exotic vortex configurations. These results correlate with current experimental efforts in multi-component Bose-Einstein condensates, and the understanding of the role of vortex interactions in multiband superconductors.Comment: Published in PR

Black Hole Formation with an Interacting Vacuum Energy Density

We discuss the gravitational collapse of a spherically symmetric massive core of a star in which the fluid component is interacting with a growing vacuum energy density. The influence of the variable vacuum in the collapsing core is quantified by a phenomenological \beta-parameter as predicted by dimensional arguments and the renormalization group approach. For all reasonable values of this free parameter, we find that the vacuum energy density increases the collapsing time but it cannot prevent the formation of a singular point. However, the nature of the singularity depends on the values of \beta. In the radiation case, a trapped surface is formed for \beta<1/2 whereas for \beta>1/2, a naked singularity is developed. In general, the critical value is \beta=1-2/3(1+\omega), where the \omega-parameter describes the equation of state of the fluid component.Comment: 9 pages, 8 figure

Influence of temperature and storage time on anthocyanin stability of grape juice treated by hot filling.

The objective of this study was to analyze the storage temperatures on anthocyanins content of grape juices bottled hot, simulating inadequate cooling and storage conditions