A scheme for symmetrization verification

We propose a scheme for symmetrization verification in two-particle systems, based on one-particle detection and state determination. In contrast to previous proposals, it does not follow a Hong-Ou-Mandel-type approach. Moreover, the technique can be used to generate superposition states of single particles

Surface Spectral Function of Momentum-dependent Pairing Potentials in a Topological Insulator: Application to Cux_xBi2_2Se3_3

We propose three possible momentum-dependent pairing potentials for candidate of topological superconductor (for example Cu$_x$Bi$_2$Se$_3$), and calculate the surface spectral function and surface density of state with these pairing potentials. We find that the first two can give the same spectral functions as the fully-gapped and node-contacted pairing potentials given in [Phys. Rev. Lett. 105, 097001], and that the third one can obtain topological non-trivial case which exists flat Andreev bound state and preserves the $C_3$ rotation symmetry. We hope our proposals and results be judged by future experiment.Comment: 5 pages, 3 figure

Compositeness effects, Pauli's principle and entanglement

We analyse some compositeness effects and their relation with entanglement. We show that the purity of a composite system increases, in the sense of the expectation values of the deviation operators, with large values of the entanglement between the components of the system. We also study the validity of Pauli's principle in composite systems. It is valid within the limits of application of the approach presented here. We also present an example of two identical fermions, one of them entangled with a distinguishable particle, where the exclusion principle cannot be applied. This result can be important in the description of open systems

Dielectric Function of Diluted Magnetic Semiconductors in the Infrared Regime

We present a study of the dielectric function of metallic (III,Mn)V diluted magnetic semiconductors in the infrared regime. Our theoretical approach is based on the kinetic exchange model for carrier induced (III,Mn)V ferromagnetism. The dielectric function is calculated within the random phase approximation and, within this metallic regime, we treat disorder effects perturbatively and thermal effects within the mean field approximation. We also discuss the implications of this calculations on carrier concentration measurements from the optical f-sum rule and the analysis of plasmon-phonon coupled modes in Raman spectra.Comment: 6 pages, 6 figures include

First Principles Studies on 3-Dimentional Strong Topological Insulators: Bi2Te3, Bi2Se3 and Sb2Te3

Bi2Se3, Bi2Te3 and Sb2Te3 compounds are recently predicted to be 3-dimentional (3D) strong topological insulators. In this paper, based on ab-initio calculations, we study in detail the topological nature and the surface states of this family compounds. The penetration depth and the spin-resolved Fermi surfaces of the surface states will be analyzed. We will also present an procedure, from which highly accurate effective Hamiltonian can be constructed, based on projected atomic Wannier functions (which keep the symmetries of the systems). Such Hamiltonian can be used to study the semi-infinite systems or slab type supercells efficiently. Finally, we discuss the 3D topological phase transition in Sb2(Te1-xSex)3 alloy system.Comment: 8 pages,17 figure

Curvature-induced anisotropic spin-orbit splitting in carbon nanotubes

We have theoretically explored the spin-orbit interaction in carbon nanotubes. We have found that, besides the dependence on chirality and diameter, the effects of spin-orbit coupling are anisotropic: spin splitting is larger for the higher valence or the lower electron band depending on the specific tube. Different tube behaviors can be grouped in three families, according to the so called chiral index. Curvature-induced changes in the orbital hybridization have a crucial role, and they are shown to be family-dependent. Our results explain recent experiments without invoking external fields

Pure spin current in a two-dimensional topological insulator

We predict a mechanism to generate a pure spin current in a two-dimensional topological insulator. As the magnetic impurities exist on one of edges of the two-dimensional topological insulator, a gap is opened in the corresponding gapless edge states but another pair of gapless edge states with opposite spin are still protected by the time-reversal symmetry. So the conductance plateaus with the half-integer values $e^2/h$ can be obtained in the gap induced by magnetic impurities, which means that the pure spin current can be induced in the sample. We also find that the pure spin current is insensitive to weak disorder. The mechanism to generate pure spin currents is generalized for two-dimensional topological insulators.Comment: 5 pages, 6 figure

Ab initio vibrations in nonequilibrium nanowires

We review recent results on electronic and thermal transport in two different quasi one-dimensional systems: Silicon nanowires (SiNW) and atomic gold chains. For SiNW's we compute the ballistic electronic and thermal transport properties on equal footing, allowing us to make quantitative predictions for the thermoelectric properties, while for the atomic gold chains we evaluate microscopically the damping of the vibrations, due to the coupling of the chain atoms to the modes in the bulk contacts. Both approaches are based on a combination of density-functional theory, and nonequilibrium Green's functions.Comment: 16 pages, to appear in Progress in Nonequilibrium Green's Functions IV (PNGF4), Eds. M. Bonitz and K. Baltzer, Glasgow, August 200

Measuring self-esteem in Spanish adolescents: Equivalence across gender and educational levels

Rosenberg's self-esteem scale (RSES) has been applied in many areas of psychology, highlighting the interest in the study of gender differences and educational level. At the same time, there was a methodological debate on its psychometric properties. Evidence points at a scale measuring a single trait confounded by a method factor associated to negatively worded items. The aim of the study is to examine RSES differences due to gender and educational level at the factor level, while controlling for the presence of method effects, in Spanish students. A completely a priori model was separately tested in four subsamples: college men and women, and high school men and women, and an invariance routine implemented for them. The primary conclusions are that the scale measures equally well in the four samples, and there were no latent mean differences due to gender or educational level. La escala de autoestima de Rosenberg (RSES) se ha empleado en muchas áreas de la psicología, destacando el interés por el estudio de las diferencias de género y de nivel educativo. Paralelamente, ha habido un debate metodológico sobre sus propiedades psicométricas: la evidencia señala que mide un solo rasgo de autoestima, pero confundido con un efecto de método asociado a los ítems invertidos. El objetivo de este estudio es examinar las diferencias en género y nivel educativo de la RSES, controlando por la presencia de efectos de método en estudiantes españoles. Se estimó un modelo completamente a priori en cuatro muestras: estudiantes hombres y mujeres de instituto y de universidad, y se implementó una rutina completa de invarianza factorial. Los principales resultados son que la escala mide de forma adecuada a las cuatro muestras y no hubo diferencias en las medias latentes en función del género o el nivel educativo

Socio-Demographic Variables and Successful Aging of the Angolan Elderly

The proportion of elderly people is growing faster than any other age group. Amongst them, the group of oldest old is indeed the segment of the elderly population with the fastest growth rate. The increase in the proportion of elderly in the Angolan population makes research on this area badly needed. Within the theoretical framework of successful aging, the study aims to test for sociodemographic group differences in perceived health, life satisfaction, and social relations in Angolan elderly. The dependent variables are three of the components of what has been called successful aging. Data came from a cross-sectional survey of elderly people living in Luanda. 1003 Angolan elderly were surveyed on sociodemographic information, perceived health, life satisfaction, and social support. MANOVAs were calculated to test for mean differences in the dependent variables. Results permit to conclude that the factors associated with the largest differences on the Angolan elderly’s quality of life and social relations were age (becoming oldest old) and institutionalization. The interactions of several factors with age pointed out that the oldest old were clearly a group in which the decreased quality of life due to becoming oldest old could not be compensated by other factors, as it was the case in the group of young old