Optimal Control of Quantum Rings by Terahertz Laser Pulses

Complete control of single-electron states in a two-dimensional semiconductor quantum-ring model is established, opening a path into coherent laser-driven single-gate qubits. The control scheme is developed in the framework of optimal control theory for laser pulses of two-component polarization. In terms of pulse lengths and target-state occupations, the scheme is shown to be superior to conventional control methods that exploit Rabi oscillations generated by uniform circularly polarized pulses. Current-carrying states in a quantum ring can be used to manipulate a two-level subsystem at the ring center. Combining our results, we propose a realistic approach to construct a laser-driven single-gate qubit that has switching times in the terahertz regime.Comment: Phys. Rev. Lett. (in print) (2007

Optimal laser-control of double quantum dots

Coherent single-electron control in a realistic semiconductor double quantum dot is studied theoretically. Using optimal-control theory we show that the energy spectrum of a two-dimensional double quantum dot has a fully controllable transition line. We find that optimized picosecond laser pulses generate population transfer at significantly higher fidelities (>0.99) than conventional sinusoidal pulses. Finally we design a robust and fast charge switch driven by optimal pulses that are within reach of terahertz laser technology.Comment: 5 pages, 4 figure

Library of high and mid-resolution spectra in the CaII H & K, Hα, Hβ, NaI D_1, D_2, and HeI D3 line regions of F, G, K and M field stars

In this work we present spectroscopic observations centered in the spectral lines most widely used as optical indicators of chromospheric activity (Hα, Hβ, CaII H & K, and HeI D_3) in a sample of F, G, K and M chromospherically inactive stars. The spectra have been obtained with the aim of providing a library of high and mid-resolution spectra to be used in the application of the spectral subtraction technique to obtain the active-chromosphere contribution to these lines in chromospherically active single and binary stars. This library can also be used for spectral classification purposes. A digital version with all the spectra is available via ftp and the World Wide Web (WWW) in both ASCII and FITS formats

Simultaneous Surface Plasmon Resonance and X-ray Absorption Spectroscopy

We present here an experimental set-up to perform simultaneously measurements of surface plasmon resonance (SPR) and X-ray absorption spectroscopy (XAS) in a synchrotron beamline. The system allows measuring in situ and in real time the effect of X-ray irradiation on the SPR curves to explore the interaction of X-rays with matter. It is also possible to record XAS spectra while exciting SPR in order to detect the changes in the electronic configuration of thin films induced by the excitation of surface plasmons. Combined experiments recording simultaneously SPR and XAS curves while scanning different parameters can be carried out. The relative variations in the SPR and XAS spectra that can be detected with this set-up ranges from 10-3 to 10-5, depending on the particular experiment

Association of Motivational Climate With Addictive Behaviors Depending on Type of Sport in University Students: Structural Equation Analysis

This research study aims at contrasting a structural model of the associations between the alcohol consumption, tobacco dependence, and the problematic use of video games with motivational climate toward sport depending on the category of sports practiced in a sample of Physical Education university students. The sample consisted of 775 university students from the Autonomous Community of Andalusia (Spain), aged between 21 and 35 (22.22 ± 3.76) years. The instruments used were the Perceived Motivational Climate in Sport Questionnaire (PMCSQ-2), the Alcohol Use Disorders Identification Test (AUDIT), the Fagerström Test for Nicotine Dependence (FTND), and the Questionnaire of Experiences Related to Video Games (QERV) questionnaires. A path model that fitted properly in the multigroup analysis for both categories of sports was used, χ2 = 19.843; gl = 8; p = .011; comparative fit index (CFI) = 0.911; normed fit index (NFI) = 0.903; incremental fit index (IFI) = 0.912; root mean square error approximation (RMSEA) = 0.085. An inverse association was shown between task climate and tobacco consumption in individual sports, being weaker in collective sports. This association is not significant for collective sports, but it is for individual sports for ego climate. However, a positive association was found between ego climate and the use of video games in individual sports, not being significant in the case of collective sports. The importance of promoting motivational climates oriented toward tasks that are based on the practice of collective sports is established, because they could act as protective factors against the development of addictive behavior in university students.This research study has been supported by the Education Innovation Project PID 16-45, named “Implementation of digital resources in the classroom for the development of psychosocial and motivational factors in students of the degree in Primary Education with the speciality in Physical Education,” funded by the University of Granada. Education Innovation Project PIBD Advanced 470, named “Program of teaching intervention in students of the degree in primary education and early childhood education through the use of new technologies for the improvement of the psychosocial factors of the students,” funded by the University of Granada. Project I+D+I “DISPERSA,” with code number TIN2015-67149-C3-R, named “Design of Pervasive Games Based on Learning Experiences Sensitive to Context” funded by the Ministry of Economy and Competitiveness. Precompetitive Research Projects for Young Researchers (PPJI_B-05); Self-plan Research of the University of Granada

Effects of the 4N(v) chromosome from Aegilops ventricosa on agronomic and quality traits in bread wheat

Advanced wheat lines carrying the Hessian fly resistance gene H27 were obtained by backcrossing the wheat/Aegilops ventricosa introgression line, H-93-33, to commercial wheat cultivars as recurrent parents. The Acph-N v 1 marker linked to the gene H27 on the 4Nv chromosome of this line was used for marker assisted selection. Advanced lines were evaluated for Hessian fly resistance in field and growth chamber tests, and for other agronomic traits during several crop seasons at different localities of Spain. The hessian fly resistance levels of lines carrying the 4Nv chromosome introgression (4D/4Nv substitution and recombination lines that previously were classified by in situ hybridisation) were high, but always lower than that of their Ae. ventricosa progenitor. Introgression lines had higher grain yields in infested field trials than those without the 4Nv chromosome and their susceptible parents, but lower grain yields under high yield potential conditions. The 4Nv introgression was also associated with later heading, and lower tiller and grain numbers/m2 . In addition, it was associated with longer and more lax spikes, and higher values of grain weight and grain protein content. However, the glutenin and gliadin expression, as well as the bread-making performance, were similar to those of their recurrent parent

Cluster-surface and cluster-cluster interactions: Ab initio calculations and modeling of van der Waals forces

We present fully ab-initio calculations of van der Waals coefficients for two different situations: i) the interaction between hydrogenated silicon clusters; and ii) the interactions between these nanostructures and a non metallic surface (a silicon or a silicon carbide surface). The methods used are very efficient, and allow the calculation of systems containing hundreds of atoms. The results obtained are further analyzed and understood with the help of simple models. These models can be of interest for molecular dynamics simulations of silicon nanostructures on surfaces, where they can give a very fast yet sufficiently accurate determination of the van der Waals interaction at large separations.Comment: Phys. Rev.

Revealing the Jet Structure of GRB 030329 with High Resolution Multicolor Photometry

We present multicolor optical observations of the nearby (z=0.1685) GRB 030329 obtained with the same instrumentation over a time period of 6 hours for a total of an unprecedented 475 quasi-simultaneous BVR observations. The achromatic steepening in the optical, which occurs at t~0.7 days, provides evidence for a dynamic transition of the source, and can be most readily explained by models in which the GRB ejecta are collimated into a jet. Since the current state-of-the-art modeling of GRB jets is still flawed with uncertainties, we use these data to critically assess some classes of models that have been proposed in the literature. The data, especially the smooth decline rate seen in the optical afterglow, are consistent with a model in which GRB 030329 was a homogeneous, sharp-edged jet, viewed near its edge interacting with a uniform external medium, or viewed near its symmetry axis with a stratified wind-like external environment. The lack of short timescale fluctuations in the optical afterglow flux down to the 0.5 per cent level puts stringent constraints on possible small scale angular inhomogeneities within the jet or fluctuations in the external density