Exciting polaritons with quantum light

We discuss the excitation of polaritons---strongly-coupled states of light and matter---by quantum light, instead of the usual laser or thermal excitation. As one illustration of the new horizons thus opened, we introduce Mollow spectroscopy, a theoretical concept for a spectroscopic technique that consists in scanning the output of resonance fluorescence onto an optical target, from which weak nonlinearities can be read with high precision even in strongly dissipative environments.Comment: 5 pages, 3 figure

Structure of the harmonic oscillator in the space of n-particle Glauber correlators

We map the Hilbert space of the quantum harmonic oscillator to the space of Glauber’s nth-order intensity correlators, in effect showing “the correlations between the correlators” for a random sampling of the quantum states. In particular, we show how the popular g(2) function is correlated to the mean population and how a recurrent criterion to identify single-particle states or emitters, namely, g(2)<1/2g(2)<1/2, actually identifies states with at most two particles on average. Our charting of the Hilbert space allows us to capture its structure in a simpler and physically more intuitive way that can be used to classify quantum sources by surveying which territory they can access

Ultrafast control of Rabi oscillations in a polariton condensate

We report the experimental observation and control of space and time-resolved light-matter Rabi oscillations in a microcavity. Our setup precision and the system coherence are so high that coherent control can be implemented with amplification or switching off of the oscillations and even erasing of the polariton density by optical pulses. The data is reproduced by a fundamental quantum optical model with excellent accuracy, providing new insights on the key components that rule the polariton dynamics.Comment: 5 pages, 3 figures, supplementary 7 pages, 4 figures. Supplementary videos: https://drive.google.com/folderview?id=0B0QCllnLqdyBNjlMLTdjZlNhbTQ&usp=sharin

Vortex dynamics controlled by local superconducting enhancement

A controlled local enhancement of superconductivity yields unexpected modifications in the vortex dynamics. This local enhancement has been achieved by designing an array of superconducting Nb nanostructures embedded in a V superconducting film. The most remarkable findings are: (i) vanishing of the main commensurability effect between the vortex lattice and the array unit cell, (ii) hysteretic behavior in the vortex dynamics, (iii) broadening of the vortex liquid phase and (iv) strong softening of the vortex lattice. These effects can be controlled and they can be quenched by reducing the Nb array superconducting performance applying an in-plane magnetic field. These results can be explained by taking into account the repulsive potential landscape created by the superconducting Nb nanostructures on which vortices move

Basin scale sources of siltation in a contaminated hydropower reservoir

Siltation and the loss of hydropower reservoir capacity is a global challenge with a predicted 26 % loss of storage at the global scale by 2050. Like in many other Latin American contexts, soil erosion constitutes one of the most significant water pollution problems in Chile with serious siltation consequences downstream. Identifying the sources and drivers affecting hydropower siltation and water pollution is a critical need to inform adaptation and mitigation strategies especially in the context of changing climate regimes e.g. rainfall patterns. We investigated, at basin scale, the main sources of sediments delivered to one of the largest hydropower reservoirs in South America using a spatio-temporal geochemical fingerprinting approach. Mining activities contributed equivalent to 9 % of total recent sediment deposited in the hydropower lake with notable concentrations of sediment-associated pollutants e.g. Cu and Mo in bed sediment between the mine tributary and the reservoir sediment column. Agricultural sources represented ca. 60 % of sediment input wherein livestock production and agriculture promoted the input of phosphorus to the lake. Evaluation of the lake sediment column against the tributary network showed that the tributary associated with both dominant anthropogenic activities (mining and agriculture) contributed substantially more sediment, but sources varied through time: mining activities have reduced in proportional contribution since dam construction and proportional inputs from agriculture have increased in recent years, mainly promoted by recent conversion of steep lands from native vegetation to agriculture. Siltation of major hydropower basins presents a global challenge exemplified by the Rapel basin. The specific challenges faced here highlight the urgent need for co-design of evidence-led, context-specific solutions that address the interplay of drivers both within and without the basin and its communities, enhancing the social acceptability of sediment management strategies to support the sustainability of clean, hydropower energy production

Frequency-resolved Monte Carlo

We adapt the Quantum Monte Carlo method to the cascaded formalism of quantum optics, allowing us to simulate the emission of photons of known energy. Statistical processing of the photon clicks thus collected agrees with the theory of frequency-resolved photon correlations, extending the range of applications based on correlations of photons of prescribed energy, in particular those of a photon-counting character. We apply the technique to autocorrelations of photon streams from a two-level system under coherent and incoherent pumping, including the Mollow triplet regime where we demonstrate the direct manifestation of leapfrog processes in producing an increased rate of two-photon emission events

Análisis de los servicios de test del VIH de cinco centros comunitarios españoles para la mejora de nuevas estrategias de promoción del diagnóstico precoz

Background: In recent years, the number of people tested for HIV has experienced a significant increase. The purpose of this study is to analyze data obtained in Spain in the HIV testing services of five Community Centres members of Agrupación Prueba de VIHda throughout 2014 and 2015,to determine its effectiveness and to characterize the subpopulation with a HIV reactive result. Study design and methods: agrupación Prueba de VIHda performed free, anonymous and confidential HIV tests according to the Consolidated guidelines on HIV testing services of WHO (2015). Data were collected using the questionnaire of the COBATEST network, developed by the COBATEST Project, and its significance was determined statistically. Results: 3061 HIV tests were performed during 2014 and 2015, with a prevalence of reactive results of 2.5%. Heterosexual and bisexual men got tested at older ages than homosexual men and women. Non-Spanish origin seems to be a risk factor for HIV infection within the sample. Bisexual men showed as high prevalence of reactive test as homosexual men, as well as they reported less previous HIV tests. Finally, index testing performed by HIV positive peer educators to the sexual partners of newly diagnosed patients showed higher prevalence than that of the classical Voluntary Counselling and Testing approach outreach most at risk populations. Conclusion:The analysis of the data shows higher prevalence of reactive results in people of non-Spanish origin compared to that of the Spanish subgroup, the former still facing barriers to access the public health system in Spain. It also demonstrates the need of new and adapted approaches for promoting early diagnosis specifically in bisexual men. Index testing by peer HIV positive educators is a highly effective method for testing people at high risk of acquiring HIV infection.Antecedentes: En los últimos años, el número de personas sometidas a pruebas frente al VIH ha experimentado un aumento significativo. El propósito de este estudio es analizar los datos de prevalencia de la infección por VIH obtenidos por cinco centros comunitarios en España pertenecientes a la Agrupación Prueba de VIHda entre 2014 y 2015, determinar su efectividad y caracterizar la subpoblación con un resultado preliminar reactivo. Diseño experimental y métodos: La Agrupación Prueba de VIHda realizó pruebas de VIH gratuitas, anónimas y confidenciales de acuerdo con las directrices consolidadas por la OMS (2015). Los datos fueron recogidos mediante el cuestionario desarrollado por el Proyecto COBATEST y su significación se determinó estadísticamente. Resultados: Durante 2014 y 2015 se realizaron un total de 3061 pruebas frente al VIH, obteniendo una prevalencia de resultados preliminares positivos del 2,5%. Los hombres heterosexuales y bisexuales se realizaron la prueba a edades más avanzadas que los hombres homosexuales y las mujeres. Las personas de origen no español parecieron mostrar un mayor riesgo de infección frente al VIH. Hombres bisexuales mostraron una prevalencia elevada similar a la de hombres homosexuales, así como declararon menos pruebas anteriores frente al VIH. Finalmente, las pruebas realizadas a través de indextesting por los educadores pares de VIH a parejas sexuales de pacientes recién diagnosticados mostraron una prevalencia superior a la obtenida por el modelo tradicional de counselling y testado voluntario ofrecido desde los centros comunitarios a poblaciones de mayor riesgo. Conclusión: El análisis de los datos muestra mayores prevalencias de resultados preliminares reactivos en personas de origen no español comparadas con aquellas del subgrupo de personas españolas, el primero de ellos todavía enfrentando barreras de acceso al sistema sanitario público en España, El análisis también demuestra la necesidad de nuevos enfoques adaptados para promover el diagnóstico precoz especialmente entre hombres bisexuales. Las pruebas realizadas a través de indextesting por educadores pares VIH positivos es un método muy eficaz para el testado de las personas con alto riesgo de contraer la infección por VIH

Dinosaur bonebed amber from an original swamp forest soil

Dinosaur bonebeds with amber content, yet scarce, offer a superior wealth and quality of data on ancient terrestrial ecosystems. However, the preserved palaeodiversity and/or taphonomic characteristics of these exceptional localities had hitherto limited their palaeobiological potential. Here, we describe the amber from the Lower Cretaceous dinosaur bonebed of Ariño (Teruel, Spain) using a multidisciplinary approach. Amber is found in both a root layer with amber strictly in situ and a litter layer mainly composed of aerial pieces unusually rich in bioinclusions, encompassing 11 insect orders, arachnids, and a few plant and vertebrate remains, including a feather. Additional palaeontological data—charophytes, palynomorphs, ostracods— are provided. Ariño arguably represents the most prolific and palaeobiologically diverse locality in which fossiliferous amber and a dinosaur bonebed have been found in association, and the only one known where the vast majority of the palaeontological assemblage suffered no or low-grade pre-burial transport. This has unlocked unprecedentedly complete and reliable palaeoecological data out of two complementary windows of preservation—the bonebed and the amber—from the same site.European Regional Development Fund (FEDER)Ministerio de Ciencia e Innovación (MICINN)/FEDERMinisterio de Economía y Competitividad (MINECO)/FEDERGeneralitat de CatalunyaGeneralitat de Catalunya/FEDERMMinisterio de Ciencia e Innovación (MICINN)Oxford UniversityAustrian Academy of SciencesUniversité de TunisGeneralitat ValencianaDepto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu