Measurement of the intrinsic damping constant in individual nanodisks of Y3Fe5O12 and Y3Fe5O12|Pt

Hahn, C. et al.We report on an experimental study on the spin-waves relaxation rate in two series of nanodisks of diameter ¿=300 , 500, and 700¿nm, patterned out of two systems: a 20¿nm thick yttrium iron garnet (YIG) film grown by pulsed laser deposition either bare or covered by 13¿nm of Pt. Using a magnetic resonance force microscope, we measure precisely the ferromagnetic resonance linewidth of each individual YIG and YIG|Pt nanodisks. We find that the linewidth in the nanostructure is sensibly smaller than the one measured in the extended film. Analysis of the frequency dependence of the spectral linewidth indicates that the improvement is principally due to the suppression of the inhomogeneous part of the broadening due to geometrical confinement, suggesting that only the homogeneous broadening contributes to the linewidth of the nanostructure. For the bare YIG nano-disks, the broadening is associated to a damping constant ¿=4¿×¿10¿4 . A threefold increase of the linewidth is observed for the series with Pt cap layer, attributed to the spin pumping effect. The measured enhancement allows to extract the spin mixing conductance found to be G¿¿¿¿=1.55¿×¿1014¿¿¿1¿m¿2 for our YIG(20nm)|Pt interface, thus opening large opportunities for the design of YIG based nanostructures with optimized magnetic losses.This research was supported by the French Grants Trinidad (ASTRID 2012 program) and by the RTRA Triangle de la Physique grant Spinoscopy.Peer Reviewe

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

Engineering and harnessing giant atoms in high-dimensional baths: a cold atoms' implementation

Emitters coupled simultaneously to distant positions of a photonic bath, the so-called giant atoms, represent a new paradigm in quantum optics. When coupled to one-dimensional baths, as recently implemented with transmission lines or SAW waveguides, they lead to striking effects such as chiral emission or decoherence-free atomic interactions. Here, we show how to create giant atoms in dynamical state-dependent optical lattices, which offers the possibility of coupling them to structured baths in arbitrary dimensions. This opens up new avenues to a variety of phenomena and opportunities for quantum simulation. In particular, we show how to engineer unconventional radiation patterns, like multi-directional chiral emission, as well as collective interactions that can be used to simulate non-equilibrium many-body dynamics with no analogue in other setups. Besides, the recipes we provide to harness giant atoms in high dimensions can be exported to other platforms where such non-local couplings can be engineered.Comment: 9 pages, 5 figures. Title changed to accommodate to the new focus of the main text. Several typos correcte

Emitters of NN-photon bundles

We propose a scheme based on the coherent excitation of a two-level system in a cavity to generate an ultrabright CW and focused source of quantum light that comes in groups (bundles) of $N$ photons, for an integer $N$ tunable with the frequency of the exciting laser. We define a new quantity, the \emph{purity} of $N$-photon emission, to describe the percentage of photons emitted in bundles, thus bypassing the limitations of Glauber correlation functions. We focus on the case $1\le N\le3$ and show that close to 100% of two-photon emission and 90% of three-photon emission is within reach of state of the art cavity QED samples. The statistics of the bundles emission shows that various regimes---from $N$-photon lasing to $N$-photon guns---can be realized. This is evidenced through generalized correlation functions that extend the standard definitions to the multi-photon level.Comment: Introduce the n-th order N-photon correlation functions. Reorganized to emphasize the N-photon emitter, now extended to the antibunching regime, rather than only coherent emission as previsoul

Impact of Fluid Substitution on the Performance of an Axial Compressor Blade Cascade Working with Supercritical Carbon Dioxide

Abstract Recent research on turbomachinery design and analysis for supercritical carbon dioxide (sCO2) power cycles has relied on computational fluid dynamics. This has produced a large number of works whose approach is mostly case-specific, rather than of general application to sCO2 turbomachinery design. As opposed to such approach, this work explores the aerodynamic performance of compressor blade cascades operating on air and supercritical CO2 with the main objective to evaluate the usual aerodynamic parameters of the cascade for variable boundary conditions and geometries, enabling “full” or “partial” similarity. The results present both the global performance of the cascades and certain features of the local flow (trailing edge and wake). The discussion also highlights the mechanical limitations of the analysis (forces exerted on the blades), which is the main restriction for applying similarity laws to extrapolate the experience gained through decades of work on air turbomachinery to the new working fluid. This approach is a step toward the understanding and appropriate formulation of a multi-objective optimization problem for the design of such turbomachinery components where sCO2 is used as the operating fluid. With this objective, the paper aims to identify and analyze what would be expected if a common description of such computational design problems similar to those where air is the working fluid were used.</jats:p

Energy evaluation of extruded compound foods for dogs by near-infrared spectroscopy

Near-infrared reflectance spectroscopy (NIRS) was used to predictthe chemical composition, the apparent digestibility and the content ofdigestible nutrients and energy of commercial extruded compoundfoods fordogs

Reducing techno-anxiety in high school teachers by improving their ICT problem-solving skills

Teachers need to continuously update their information and communication technologies (ICT) knowledge, but they are usually not trained to deal with the problems arising from their use. In fact, studies in the literature report techno-anxiety (i.e. unpleasant physiological activation and discomfort due to present or future use of ICT) in teachers. Thus, the goal of this action research is to study if teachers’ techno-anxiety can be reduced by increasing their ability to solve technological problems. An inter-subject experiment has been carried out with 46 teachers. High school teachers were chosen because they are digital immigrants, while at the moment of this research their students are digital natives (born around year 2000). Since we could not find any specific training for teachers to increase their resolution skills of technological problems, in order to apply the treatment for our study, we have designed and deployed an online course about ICT problem-solving skills based on the 70/20/10 model for learning and development. Results show the success of the course when it comes to increasing the ICT problem-solving skills and to reducing techno-anxiety.Preprin

Estadística Descriptiva y Probabilidad: (Teoría y problemas)

XXXIV, 261 p. ; 24 cm.Libro ElectrónicoÍndice Bibliografía: p. [256]-258 Manual para alumnos de titulaciones experimentales que proporciona una visión práctica e intuitiva de la estadística descriptiva y el cálculo de probabilidades, campos básicos y fundamentales de la ciencia estadísticaLibro : Español (spa) : 3a. edIndice general Prólogo XIII 1. Introducción XIII 2. History (Histórico) XV 3. Licencia de Documentación Libre de GNU XVI 4. GNU Free Documentation License XXVI A Estadística Descriptiva 1 1 Síntesis de la información 7 1. Rese˜na histórica 7 2. La organización de la información 9 3. Representaciones grá?cas 15 4. Medidas centrales 17 5. Medidas de posición 26 6. Medidas de dispersión 27 7. Desigualdad de Tchebychev 31 8. Momentos de la distribución 31 9. Medidas de forma 33 10. Transformaciones 36 11. Análisis exploratorio de datos 37 12. Ejercicios 40 2 Análisis conjunto de variables. 53 1. Distribución conjunta de dos caracteres 53 2. Distribuciones marginales 55 3. Distribuciones condicionadas 55 4. Independencia 60 5. Medidas de dependencia. Coeficientes de relación 61 6. Ejercicios 78 3 Ajuste y regresión bidimensional 89 1. Introducción 89 2. Ajuste. Criterio de los mínimos cuadrados 91 3. Análisis de la bondad del ajuste 97 4. Regresión. Método de regresión a la media 100 5. Análisis de la bondad de la regresión 102 6. Notas y conclusiones 104 7. Ejercicios 105 B Probabilidad 113 4 Teoría de la probabilidad 117 1. Evolución histórica 117 2. Conjuntos. Operaciones 120 3. Algebra de sucesos 122 4. Distintas de?niciones del concepto de probabilidad 126 5. Propiedades de la función de probabilidad 129 6. Probabilidad condicionada. Independencia 131 7. Dependencia e independencia 132 8. Teorema de la probabilidad total. Teorema de Bayes 133 9. Ejercicios 136 5 Variable aleatoria 145 1. Concepto 145 2. Variables discretas y continuas 146 3. Variables unidimensionales 147 4. Variables multidimensionales 161 5. Ejercicios 173 6 Algunos modelos probabilísticos 185 1. Distribución uniforme discreta 185 2. Experimento de Bernouilli 186 3. Distribución hipergeométrica 191 4. Proceso de Poisson 192 5. Distribución uniforme continua 195 6. Distribución normal 197 7. Relación entre binomial, Poisson y normal 200 8. Teorema central del límite 201 9. Distribución gamma 202 10. Distribución beta 203 11. Distribución de Cauchy 204 12. Distribuciones derivadas de la normal 206 13. Distribución de Laplace 210 14. Distribución logística 211 15. Distribución de Pareto 211 16. Algunos modelos multidimensionales 212 17. Ejercicios 215 A Combinatoria 225 1. Introducción 225 2. Variaciones con repetición 225 3. Variaciones 226 4. Permutaciones 226 5. Permutaciones con repetición 226 6. Combinaciones sin repetición 227 7. Combinaciones con repetición 228 8. Ejercicios 228 B Tablas Estadísticas 233 C Bibliografía 25