Self-consistent characterization of light statistics

We demonstrate the possibility of a self-consistent characterization of the photon-number statistics of a light field by using photoemissive detectors with internal gain simply endowed with linear input/output responses. The method can be applied to both microscopic and mesoscopic photon-number regimes. The detectors must operate in the linear range without need of photon-counting capabilities.Comment: To be published in "Journal of Modern Optics

3D phase-matching conditions for the generation of entangled triplets by chi(2) interlinked interactions

An analytical calculation of the interaction geometry of two interlinked second-order nonlinear processes fulfilling phase-matching conditions is presented. The method is developed for type-I uniaxial crystals and gives the positions on a screen beyond the crystal of the entangled triplets generated by the interactions. The analytical results are compared to experiments realized in the macroscopic regime. Preliminary tests to identify the triplets are also performed based on intensity correlations.Comment: 6 pages, 3 figures, 1 movie (extension of fig. 2

Photon-number correlations by photon-number resolving detectors

We demonstrate that by using a pair of photodetectors endowed with internal gain we are able to quantify the correlation coefficient between the two components of a pulsed bipartite state in the mesoscopic intensity regime (less than 100 mean photons)

Explorando un espacio desconocido: Prensa de mujeres en Chile, 1900-1920.

¿Por qué pues permaneceremos frías espectadoras del drama político que ha principiado a representarse en la Cámara de Diputados, y que podrá muy bien tener por teatro a toda la República? ¿Porque somos señoras? No"1. La prensa como medio de comunicación moderno se desarrolla en Chile a partir de las primeras décadas del siglo XX. El proceso de modernización que trajo cambios económicos, políticos, sociales y culturales, permitió la irrupción en el espacio social de diversos grupos sociales; la prensa caracterizará las comunicaciones de la época como canal de conducción de ideas y como un espacio de participación social. Hacia el inicio del siglo la prensa por primera vez tendrá públicos específicos y se desarrollará dentro de una empresa editorial de acuerdo a las demandas específicas de públicos diferenciados .2 En este contexto, las mujeres desarrollarán una prensa propia, de mujeres para mujeres, de acuerdo a intereses específicos. Si bien es cierto que existen antecedentes a partir de la segunda mitad del siglo XIX del desarrollo de una prensa femenina, es a partir de 1900 cuando esta producción periodística se diversifica tanto en relación al origen social de las productoras, como en los objetivos de las publicaciones

Multiphoton communication in lossy channels with photon-number entangled states

We address binary and quaternary communication channels based on correlated multiphoton two-mode states of radiation in the presence of losses. The protocol are based on photon number correlations and realized upon choosing a shared set of thresholds to convert the outcome of a joint photon number measurement into a symbol from a discrete alphabet. In particular, we focus on channels build using feasible photon-number entangled states (PNES) as two-mode coherently-correlated (TMC) or twin-beam (TWB) states and compare their performances with that of channels built using feasible classically correlated (separable) states. We found that PNES provide larger channel capacity in the presence of loss, and that TWB-based channels may transmit a larger amount of information than TMC-based ones at fixed energy and overall loss. Optimized bit discrimination thresholds, as well as the corresponding maximized mutual information, are explicitly evaluated as a function of the beam intensity and the loss parameter. The propagation of TMC and TWB in lossy channels is analyzed and the joint photon number distribution is evaluated, showing that the beam statistics, either sub-Poissonian for TMC or super-Poissonian for TWB, is not altered by losses. Although entanglement is not strictly needed to establish the channels, which are based on photon-number correlations owned also by separable mixed states, purity of the support state is relevant to increase security. The joint requirement of correlation and purity individuates PNES as a suitable choice to build effective channels. The effects of losses on channel security are briefly discussed.Comment: 8 pages, 19 figure

Statistical analysis on testing of an entangled state based on Poisson distribution framework

A hypothesis testing scheme for entanglement has been formulated based on the Poisson distribution framework instead of the POVM framework. Three designs were proposed to test the entangled states in this framework. The designs were evaluated in terms of the asymptotic variance. It has been shown that the optimal time allocation between the coincidence and anti-coincidence measurement bases improves the conventional testing method. The test can be further improved by optimizing the time allocation between the anti-coincidence bases.Comment: This paper is an extended version of the theoretical part of v1 of quant-ph/0603254.quant-ph/0603254 is revised so that it is more familiar to experimentalist

Photon-number statistics with Silicon photomultipliers

We present a description of the operation of a multi-pixel detector in the presence of non-negligible dark-count and cross-talk effects. We apply the model to devise self-consistent calibration strategies to be performed on the very light under investigation

Measurement of two-mode squeezing with photon number resolving multi-pixel detectors

The measurement of the two-mode squeezed vacuum generated in an optical parametric amplifier (OPA) was performed with photon number resolving Multi-Pixel Photon Counters (MPPCs). Implementation of the MPPCs allows for the observation of noise reduction in a broad dynamic range of the OPA gain, which is inaccessible with standard single photon avalanche photodetectors.Comment: Accepted for Optics Letter

Seventh Monograph in Resilience and Health, Centre for Resilience and Socio-Emotional Health

This report presents the findings of semi- randomised evaluation of the Promoting Mental Health in School (PROMEHS) programme, developed by a nine-partners European consortium funded by the EU. The evaluation with more than 10,000 students from six different countries examined whether the progrmme is effective in enhancing students’ social and emotional learning, resilience, mental health, and academic outcomes and whether the teachers implementing the programme reported enhanced social and emotional competence, resilience, and self-efficacy.peer-reviewe