Positively charged magneto-excitons in a semiconductor quantum well

A variational calculation of the lower singlet and triplet states of positively charged excitons (trions) confined to a single quantum well and in the presence of a perpendicular magnetic field is presented. We study the dependence of the energy levels and of the binding energy on the well width and on the magnetic field strength. Our results are compared with the available experimental data and show a good qualitative and quantitative agreement. A singlet-triplet crossing is found which for a 200 \AA wide GaAs is predicted to occur for B = 15 T.Comment: 5 figs. Submitted to PR

Creating temperature dependent Ni-MH battery models for low power mobile devices

In this paper the methodology and the results of creating temperature dependent battery models for ambient intelligence applications is presented. First the measurement technology and the model generation process is presented in details, and then the characteristic features of the models are discussed.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Positronic complexes with unnatural parity

The structure of the unnatural parity states of PsH, LiPs, NaPs and KPs are investigated with the configuration interaction and stochastic variational methods. The binding energies (in hartree) are found to be 8.17x10-4, 4.42x10-4, 15.14x10-4 and 21.80x10-4 respectively. These states are constructed by first coupling the two electrons into a configuration which is predominantly 3Pe, and then adding a p-wave positron. All the active particles are in states in which the relative angular momentum between any pair of particles is at least L = 1. The LiPs state is Borromean since there are no 3-body bound subsystems (of the correct symmetry) of the (Li+, e-, e-, e+) particles that make up the system. The dominant decay mode of these states will be radiative decay into a configuration that autoionizes or undergoes positron annihilation.Comment: 10 pages RevTeX, 6 figures, in press Phys.Rev.

Optical Phonon Anomaly in Bilayer Graphene with Ultrahigh Carrier Densities

Electron-phonon coupling (EPC) in bilayer graphene (BLG) at different doping levels is studied by first-principles calculations. The phonons considered are long-wavelength high-energy symmetric (S) and antisymmetric (AS) optical modes. Both are shown to have distinct EPC-induced phonon linewidths and frequency shifts as a function of the Fermi level $E_F$. We find that the AS mode has a strong coupling with the lowest two conduction bands when the Fermi level $E_F$ is nearly 0.5 eV above the neutrality point, giving rise to a giant linewidth (more than 100 cm$^{-1}$) and a significant frequency softening ($\sim$ 60 cm$^{-1}$). Our \emph{ab initio} calculations show that the origin of the dramatic change arises from the unusual band structure in BLG. The results highlight the band structure effects on the EPC in BLG in the high carrier density regime.Comment: 5 pages, 4 figure

Comments concerning the paper "Measurement of negatively charged pion spectra in inelastic p+p interactions at 20, 31, 40, 80 and 158 GeV/c" by the NA61 collaboration

New data from the NA61 collaboration on the production of negative pions in p+p interactions at beam momenta between 20 and 158 GeV/c are critically compared to available results in the same energy range. It is concluded that the NA61 data show some discrepancies with the previous results. This concerns in particular the total yields, the $p_T$ integrated rapidity distributions and the double differential cross sections.Comment: 16 pages, 13 figure

Stability of Few-Charge Systems in Quantum Mechanics

We consider non-relativistic systems in quantum mechanics interacting through the Coulomb potential, and discuss the existence of bound states which are stable against spontaneous dissociation into smaller atoms or ions. We review the studies that have been made of specific mass configurations and also the properties of the domain of stability in the space of masses or inverse masses. These rigorous results are supplemented by numerical investigations using accurate variational methods. A section is devoted to systems of three arbitrary charges and another to molecules in a world with two space-dimensions.Comment: 101 pages, review articl

On Renyi entropies characterizing the shape and the extension of the phase space representation of quantum wave functions in disordered systems

We discuss some properties of the generalized entropies, called Renyi entropies and their application to the case of continuous distributions. In particular it is shown that these measures of complexity can be divergent, however, their differences are free from these divergences thus enabling them to be good candidates for the description of the extension and the shape of continuous distributions. We apply this formalism to the projection of wave functions onto the coherent state basis, i.e. to the Husimi representation. We also show how the localization properties of the Husimi distribution on average can be reconstructed from its marginal distributions that are calculated in position and momentum space in the case when the phase space has no structure, i.e. no classical limit can be defined. Numerical simulations on a one dimensional disordered system corroborate our expectations.Comment: 8 pages with 2 embedded eps figures, RevTex4, AmsMath included, submitted to PR

Production of Knowledge and Geographically Mediated Spillovers from Universities: Spatial Econometric Perspective and Evidence from Austria

The paper sheds some light on the issue of geographically mediated knowledge spillovers from university research activities to regional knowledge production in the high tech sector in Austria. Knowledge spillovers occur because knowledge created by university is typically not contained within that institution, and thereby creates value for others. The conceptual framework for analysing geographic spillovers of university research on regional knowledge production is derived from Griliches (1979). It is assumed that knowledge production in the high tech sector essentially depends on two major sources of knowledge: the university research that represents the potential pool of knowledge spillovers and R&D performed by the high tech sector itself. Knowledge is measured in terms of patents, university research and R&D in terms of expenditures. We refine the standard %0D knowledge production function by modelling research spillovers as a spatially discounted external stock of knowledge. This enables us to capture local and interlocal spillovers. Using district-level data and employing spatial econometric tools evidence is found of university research spillovers that transcend the geographic scale of the political district in Austria. It is shown that geographic boundedness of the spillovers is linked to a decay effect. Reference Griliches Z. (1979): Issues in Assessing the Contribution of Research and Development to Productivity Growth, Bell Journal of Economics 10, 92-116