“Fantasmas” na mecânica quântica

CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCan you pick a complex subject in quantum mechanics and discuss it with a minimum number of equations, in a simplified form that the general scientific public could understand? This was a question presented to graduate students of the one-year Quantum Mechanics course based on the text book Modern Quantum Mechanics by J. J. Sakurai and Jim Napolitano, at the State University of Campinas (UNICAMP), Brazil. The first seven authors of this paper are graduate students (alphabetical order) that accepted to try it. The chosen subject was "delocalized quantum states", and it will be discussed using colloquial terms like quantum ghosts, spooky action, splitting beings and invisibility cloak. © Sociedade Brasileira de Física. Printed in Brazil.Can you pick a complex subject in quantum mechanics and discuss it with a minimum number of equations, in a simplified form that the general scientific public could understand? This was a question presented to graduate students of the one-year Quantum Mechanics course based on the text book Modern Quantum Mechanics by J. J. Sakurai and Jim Napolitano, at the State University of Campinas (UNICAMP), Brazil. The first seven authors of this paper are graduate students (alphabetical order) that accepted to try it. The chosen subject was "delocalized quantum states", and it will be discussed using colloquial terms like quantum ghosts, spooky action, splitting beings and invisibility cloak.383111CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOSem informaçãoSem informaçãoSem informaçãoPode-se escolher um topico complexo em mecanica quantica e discuti-lo com um numero mınimo de equações, e de forma simplificada para que um publico com apenas conhecimento basico em fısica possa entender? Essa foi a pergunta apresentada aos alunos de pos-graduação das disciplinas de um ano de Mecanica Quantica I e II da Universidade Estadual de Campinas (UNICAMP), baseadas no livro “Quantum Mechanics” de J. J. Sakurai e Jim Napolitano. Os primeiros sete autores desse artigosão os alunos de pos-graduação (em ordem alfabetica) que aceitaram o desafio. O topico escolhido foi estados quanticos delocalizados, e sera discutido utilizando termos coloquiais como fantasmas quanticos, ações fantasmagoricas, entidades divididas e capa de invisibilidade.G.M.A., D.T.M, M.M. and M.A.P.L acknowledge support from the Brazilian agency “Conselho Nacional de Desenvolvimento Científico e Tecnológico” (CNPq). D.Q.A., L.F.M.C, and S.I.C.G acknowledge support from the Brazilian agency “Coordenação de Aperfeiçoamento de Pessoal de Nível Superior” (CAPES), and L.F.C.F acknowledges support from the Brazilian state of São Paulo agency “Fundação de Amparo à Pesquisa do Estado de São Paulo” (FAPESP). The authors thank Amanda A. R. Lima for drawing the inspiring figure 2. The authors are grateful to Profs. Michael Brunger, Prof. Amir Caldeira and Prof. José A. Roversi for their critical reading of the manuscript and constructive comments and suggestions. The authors also thank for critical reading of this manuscript, the following group of people of the aimed public target: Paulo S. P. Lima (Mechanical Engineer), Martín E. Navarro Maldonado (Chemical Engineer), and Luis Quesada (Professor of Computer Science and Informatics)

Noncommutative cosmological models coupled to a perfect fluid and a cosmological constant

In this work we carry out a noncommutative analysis of several Friedmann-Robert-Walker models, coupled to different types of perfect fluids and in the presence of a cosmological constant. The classical field equations are modified, by the introduction of a shift operator, in order to introduce noncommutativity in these models. We notice that the noncommutative versions of these models show several relevant differences with respect to the correspondent commutative ones.Comment: 27 pages. 7 figures. JHEP style.arXiv admin note: substantial text overlap with arXiv:1104.481

Expedição Safra Brasília: maracujá.

Capítulo 1. Inovação e Avaliação; Capítulo 2. Aspectos Teóricos da Elaboração do Método de Avaliação; Capítulo 3. Método e Aplicação do Diagnóstico Comportamental a Produtores de Maracujá do Distrito Federal; Capítulo 4. Plano de Análise Aplicado ao Diagnóstico Comportamental da Atividade Produtiva; Capítulo 5. Construção e Utilização de Planilha Eletrônica em Formato off-line: coleta de dados no campo;Anexo I. Instrumento de mensuração relacionado à cultura do maracujá; Anexo II. Exemplo de documento voltado à apresentação dos resultados.bitstream/item/202099/1/Livro-expedicao-Volume-1-2a-edicao.pdf2. ed. rev. e ampl

Wave-packet dynamics in slowly perturbed crystals: Gradient corrections and Berry-phase effects

We present a unified theory for wave-packet dynamics of electrons in crystals subject to perturbations varying slowly in space and time. We derive the wave-packet energy up to the first order gradient correction and obtain all kinds of Berry-phase terms for the semiclassical dynamics and the quantization rule. For electromagnetic perturbations, we recover the orbital magnetization energy and the anomalous velocity purely within a single-band picture without invoking inter-band couplings. For deformations in crystals, besides a deformation potential, we obtain a Berry-phase term in the Lagrangian due to lattice tracking, which gives rise to new terms in the expressions for the wave-packet velocity and the semiclassical force. For multiple-valued displacement fields surrounding dislocations, this term manifests as a Berry phase, which we show to be proportional to the Burgers vector around each dislocation.Comment: 12 pages, RevTe

Dynamic Phase Transition in a Time-Dependent Ginzburg-Landau Model in an Oscillating Field

The Ginzburg-Landau model below its critical temperature in a temporally oscillating external field is studied both theoretically and numerically. As the frequency or the amplitude of the external force is changed, a nonequilibrium phase transition is observed. This transition separates spatially uniform, symmetry-restoring oscillations from symmetry-breaking oscillations. Near the transition a perturbation theory is developed, and a switching phenomenon is found in the symmetry-broken phase. Our results confirm the equivalence of the present transition to that found in Monte Carlo simulations of kinetic Ising systems in oscillating fields, demonstrating that the nonequilibrium phase transition in both cases belongs to the universality class of the equilibrium Ising model in zero field. This conclusion is in agreement with symmetry arguments [G. Grinstein, C. Jayaprakash, and Y. He, Phys. Rev. Lett. 55, 2527 (1985)] and recent numerical results [G. Korniss, C.J. White, P. A. Rikvold, and M. A. Novotny, Phys. Rev. E (submitted)]. Furthermore, a theoretical result for the structure function of the local magnetization with thermal noise, based on the Ornstein-Zernike approximation, agrees well with numerical results in one dimension.Comment: 16 pp. RevTex, 9 embedded ps figure