A conjugate for the Bargmann representation

In the Bargmann representation of quantum mechanics, physical states are mapped into entire functions of a complex variable z*, whereas the creation and annihilation operators $\hat{a}^\dagger$ and $\hat{a}$ play the role of multiplication and differentiation with respect to z*, respectively. In this paper we propose an alternative representation of quantum states, conjugate to the Bargmann representation, where the roles of $\hat{a}^\dagger$ and $\hat{a}$ are reversed, much like the roles of the position and momentum operators in their respective representations. We derive expressions for the inner product that maintain the usual notion of distance between states in the Hilbert space. Applications to simple systems and to the calculation of semiclassical propagators are presented.Comment: 15 page

Metal-Insulator Transition in a Disordered Two-Dimensional Electron Gas in GaAs-AlGaAs at zero Magnetic Field

A metal-insulator transition in two-dimensional electron gases at B=0 is found in Ga(Al)As heterostructures, where a high density of self-assembled InAs quantum dots is incorporated just 3 nm below the heterointerface. The transition occurs at resistances around h/e^2 and critical carrier densities of 1.2 10^11cm^-2. Effects of electron-electron interactions are expected to be rather weak in our samples, while disorder plays a crucial role.Comment: 4 pages, 3 figures, 21 reference

Demonstration of the Complementarity of One- and Two-Photon Interference

The visibilities of second-order (single-photon) and fourth-order (two-photon) interference have been observed in a Young's double-slit experiment using light generated by spontaneous parametric down-conversion and a photon-counting intensified CCD camera. Coherence and entanglement underlie one-and two-photon interference, respectively. As the effective source size is increased, coherence is diminished while entanglement is enhanced, so that the visibility of single-photon interference decreases while that of two-photon interference increases. This is the first experimental demonstration of the complementarity between single- and two-photon interference (coherence and entanglement) in the spatial domain.Comment: 21 pages, 7 figure

Detection of two endornavirus in common bean genotypes in Brazil.

Endornaviruses (Endornaviridae) are persistent viruses that infect important crops such as pepper, rice, broad bean, and beans. However, these viruses are poorly studied and have not yet been reported in Brazil. In this study, we investigated the occurrence of two endornaviruses, Phaseolus vulgaris endornavirus-1 (PvEV-1) and Phaseolus vulgaris endornavirus-2 (PvEV-2) in bean genotypes

Determinação da resistência de genótipos de capsicum spp. a viroses em campo.

O objetivo desse trabalho foi avaliar a resistência de campo de 26 genótipos de Capsicum spp., incluindo 4 linhagens de pimenta malagueta (C. frutescens L.), 3 de jalapeño amarelo (C. annuum L. var. annuum), 7 de habanero e 3 de biquinho salmão (C. chinense Jacq.) e, sete cultivares de diferentes tipos de pimentas da Embrapa (BRS Moema; BRS Garça; BRS Sarakura; BRS Mari; BRS Ema; BRS Seriema; BRS Brasilândia).Resumo 7

Aharonov-Bohm signature for neutral excitons in type-II quantum dot ensembles

It is commonly believed that the Aharonov-Bohm (AB) effect is a typical feature of the motion of a charged particle interacting with the electromagnetic vector potential. Here we present a magnetophotoluminescence study of type-II InP/GaAs self-assembled quantum dots, unambiguously revealing the Aharonov-Bohm-type oscillations for neutral excitons when the hole ground state changes its angular momentum from lh = 0 to lh = 1, 2, and 3. The hole ring parameters derived from a simple model are in excellent agreement with the structural parameters for this system.Comment: Revised version, 10 pages, 3 figure

Estrutura espacial de uma comunidade de espécies arbóreas, em uma floresta densa de terra firme na Amazônia Ocidental, Brasil.

Investigar a influência de variáveis de solos na distribuição espacial da comunidade de espécies arbóreas tropicais e detectar em qual escala de tamanho de amostra a relação espécie-ambiente pode ser melhor observada

An Algebraic q-Deformed Form for Shape-Invariant Systems

A quantum deformed theory applicable to all shape-invariant bound-state systems is introduced by defining q-deformed ladder operators. We show these new ladder operators satisfy new q-deformed commutation relations. In this context we construct an alternative q-deformed model that preserve the shape-invariance property presented by primary system. q-deformed generalizations of Morse, Scarf, and Coulomb potentials are given as examples