Maximally Entangled Mixed-State Generation via Local Operations

We present a general theoretical method to generate maximally entangled mixed states of a pair of photons initially prepared in the singlet polarization state. This method requires only local operations upon a single photon of the pair and exploits spatial degrees of freedom to induce decoherence. We report also experimental confirmation of these theoretical results.Comment: 5 pages, 2 figures, to be published in Physical Review

Optimal experiment design revisited: fair, precise and minimal tomography

Given an experimental set-up and a fixed number of measurements, how should one take data in order to optimally reconstruct the state of a quantum system? The problem of optimal experiment design (OED) for quantum state tomography was first broached by Kosut et al. [arXiv:quant-ph/0411093v1]. Here we provide efficient numerical algorithms for finding the optimal design, and analytic results for the case of 'minimal tomography'. We also introduce the average OED, which is independent of the state to be reconstructed, and the optimal design for tomography (ODT), which minimizes tomographic bias. We find that these two designs are generally similar. Monte-Carlo simulations confirm the utility of our results for qubits. Finally, we adapt our approach to deal with constrained techniques such as maximum likelihood estimation. We find that these are less amenable to optimization than cruder reconstruction methods, such as linear inversion.Comment: 16 pages, 7 figure

Entangled mixed-state generation by twin-photon scattering

We report novel experimental results on mixed-state generation by multi-mode scattering of polarization-entangled photons. By using a large variety of scattering media we obtain two markedly different classes of scattered states; namely Werner-like and sub-Werner-like states. Our experimental findings are in excellent agreement with a phenomenological model based upon the description of a scattering process as a quantum map

Bragg Scattering as a Probe of Atomic Wavefunctions and Quantum Phase Transitions in Optical Lattices

We have observed Bragg scattering of photons from quantum degenerate $^{87}$Rb atoms in a three-dimensional optical lattice. Bragg scattered light directly probes the microscopic crystal structure and atomic wavefunction whose position and momentum width is Heisenberg-limited. The spatial coherence of the wavefunction leads to revivals in the Bragg scattered light due to the atomic Talbot effect. The decay of revivals across the superfluid to Mott insulator transition indicates the loss of superfluid coherence.Comment: 5 pages, 4 figure

Phenylenevinylene Systems: The Oligomer Approach

Among conducting polymers, poly-p-phenylenevinylenes (PPVs) have attained a special place in polymer electronics. The optoelectronic properties initially exposed by PPVs in organic light-emitting diodes (OLEDs) turned these organic electronic conjugated systems from the solo academic interest into a technologically very promising area. The easiness of the tuning of their optoelectronic properties through synthetic modifications make PPVs an outstanding and suitable compound for technological applications and fundamental science development. Unfortunately, the synthesis and structural optoelectronic characterization of novel PPVs is a long and difficult task that sometimes yields unclear results. However, phenylenevinylene oligomers (oPV) can be synthesized and characterized in a very straightforward manner, and their performance in novel applications can be directly related to their structural analogue polymer, methodology designated as the oligomer approach. Herein, we describe the oligomer approach using the Mizoroki-Heck reaction as a synthetic route for oPVs and PPVs, and the importance of an extensive characterization for novel applications, such as photocatalysis and matrix-assisted laser desorption/ionization (MALDI) matrices, where these electronic conjugated systems have very promising applications

Descripción de la metodología para la puesta e valor turística de 12 sitios arqueológicos en la provincia de Catamarca

Con el objetivo de generar un conjunto de datos que fijen las líneas prioritarias para la puesta en valor de los sitios arqueológicos de la Provincia de Catamarca; el presente trabajo se elaboro en base a la aplicación de una metodología capaz de generar una serie de datos duros sobre el estado actual de 12 sitios y/o yacimientos, tratando de fijar en el proceso, los principios básicos para su gestión de manera sostenible, respetando las condiciones del entorno, así como a las comunidades del lugar. El debate respecto de las técnicas de control, limitando el impacto de uso, ofreciendo al mismo tiempo el máximo disfrute a todos los visitantes posibles, sin contravenir las limitaciones impuestas por las condiciones ambientales y sociales, es una de las ambiciones a lograr; así como el diagnóstico sobre diferentes enfoques o zonificaciones para la planificación e implantación de infraestructura mínima de servicios turísticos en el área protegida de cada sitio. La orientación sobre definición, evaluación, gestión y uso de los datos de impacto turístico obtenido en cada uno de los sitios, ha respondido en todos los casos en la tendencia a mejorar la calidad de la experiencia turística, de la conservación de la diversidad biológica y cultural, y de contribuir al desarrollo de las comunidades locales. Estratégicamente, y a los efectos de considerar la puesta en valor de cada sitio arqueológico, se propone el marco de acción del Limite de Cambio Aceptable (LAC en su sigla inglesa), como una manera de trabajo concreta para la gestión de visitantes, con relación a establecer metas y cualquier acción posterior a su establecimiento para el turismo de áreas protegidas, ofreciendo una manera de acción que no se centra tanto en las relaciones entre los niveles de uso y de impacto, sino en determinar las condiciones ambientales y sociales deseables para la actividad de los visitantes y las actividades gestoras requeridas para alcanzar esas condiciones, utilizando un proceso sistemático, explícito, defendible y racional.Tópico 7: Patrimonio Arqueológico. Técnicas de evaluación, datación y conservación

Characterization of a birnavirus isolated from diseased turbot cultured in Spain

7 pages, 5 figures, 2 tables.During 1989, light but persistent mortalities were detected in a turbot Scophthalmus maximus L. farm in Galicia (northwestern Spain) and a virus with the characteristics of a birnavirus was isolated. The purpose of this study was to characterize the viral agent and determine the susceptibility of turbot to this virus. Electron microscopic examination revealed that the particles were isometric, hexagonal and unenveloped with an average diameter of 58 to 60 nm. The molecular weights of the RNA segments were 1.9 and 2.0 x 10(up to 6) daltons. The cells most susceptible to the turbot isolate were the CHSE-214, FHM and RTG-2 lines and the optimal temperature range for its replication was 15 to 2OºC. The RNA and polypeptide electropherotypes show that this virus resembles the Ab serotype of infectious pancreatic necrosis virus (IPNV); however, it differs in that it replicates in the FHM cell line and is not neutralized by antisera to the classical serotypes of IPNV. Infectivity trials conducted in turbot of dlfferent sizes indicated that the virus produced mortality only in small fish (2 g), although the larger fish (30 g) harbored the virus for at least 35 d. Fish inoculated with this isolate showed no pancreatic necrosis although necrosis of the hematopoietic elements of the kidney and spleen was detected.This work was supported by Grants MAR 89-0270 from the Comision Interministenal de Ciencia y Tecnologia (CICYT), and by XUGA 70708888 from Xunta de Galicia, Spain. Beatriz Novoa acknowledges the Ministerio de Educacion y Ciencia (Spain) for a research fellowship.Peer reviewe

When are females dominant over males in rats (Rattus norvegicus)?

Funding was provided to MAP-E (scholarship program 783–2017 of the Ministry of Science, Technology and Innovation – Minciencias, formerly Colciencias), and to CKH (Lucie Burgers Foundation grant, for the research project titled “Sex and competitive dynamics in groups of rats: is there resemblance to primates?”).In group-living animals, males are assumed to be dominant over females when they are larger than females. Despite this, females have sometimes been proven to be dominant over some males possibly via the winner-loser effect, which becomes clearer when the intensity of aggression in the group is higher. To test whether the winner-loser effect can lead to (partial) female dominance in a species with a pronounced sexual dimorphism, we studied the hierarchy in 12 rat colonies (Rattus norvegicus) in which the rats could freely interact with their group members within a spacious area. To investigate the underlying mechanisms, we compared the empirical data to hypotheses generated by the agent-based model ‘DomWorld’. We show that females dominated on average 55% of the males, and occupied the alpha position in four colonies, in three of them they shared it with one or several males. Moreover, in line with the predictions of the computational model, females dominated a higher percentage of males when the intensity of aggression of the colony was higher. This shows that although females are only half as heavy as males, they dominate part of the males probably through the winner-loser effect. We suggest that this effect may be widespread in many other species and can be tested experimentally.Peer reviewe