Oscillatons revisited

In this paper, we study some interesting properties of a spherically symmetric oscillating soliton star made of a real time-dependent scalar field which is called an oscillaton. The known final configuration of an oscillaton consists of a stationary stage in which the scalar field and the metric coefficients oscillate in time if the scalar potential is quadratic. The differential equations that arise in the simplest approximation, that of coherent scalar oscillations, are presented for a quadratic scalar potential. This allows us to take a closer look at the interesting properties of these oscillating objects. The leading terms of the solutions considering a quartic and a cosh scalar potentials are worked in the so called stationary limit procedure. This procedure reveals the form in which oscillatons and boson stars may be related and useful information about oscillatons is obtained from the known results of boson stars. Oscillatons could compete with boson stars as interesting astrophysical objects, since they would be predicted by scalar field dark matter models.Comment: 10 pages REVTeX, 10 eps figures. Updated files to match version published in Classical and Quantum Gravit

Entropic Entanglement Criteria for Continuous Variables

We derive several entanglement criteria for bipartite continuous variable quantum systems based on the Shannon entropy. These criteria are more sensitive than those involving only second-order moments, and are equivalent to well-known variance product tests in the case of Gaussian states. Furthermore, they involve only a pair of quadrature measurements, and will thus should prove extremely useful the experimental identification of entanglement.Comment: 4 pages, 2 figure

Ocorrência de murcha por Fusarium em meloeiros no Nordeste Paraense.

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Relações interpessoais dos agricultores parceiros do Projeto Tipitamba, da Embrapa Amazônia Oriental.

Neste trabalho aplicou-se a sociometria moreniana para identificar a rede de comunicação interpessoal dos agricultores parceiros do projeto Tipitamba, da Embrapa Amazônia Oriental, que trabalha a temática agricultura sem queima e estão localizados em comunidades rurais, nos municípios de Igarapé-Açu e Marapanim, no nordeste paraense. Foram coletados dados nas comunidades de São João, Novo Brasil, Nova Olinda, Aparecida e Nossa Senhora do Rosário. Utilizaram-se perguntas abertas por meio de um roteiro pré-estabelecido que oportunizasse a elaboração do sociograma dos agricultores entrevistados referente às interações política, afetiva e técnica, bem como, conhecer e identificar as razões que os levam a se comunicar na comunidade. Os resultados apontam que nas comunidades envolvidas no estudo, as pessoas mantêm baixo nível de interação/comunicação interpessoal o que certamente impede o surgimento de novas lideranças locais, à integração entre os grupos e o fortalecimento das atividades coletivas nas comunidades

Quantum metrology at the Heisenberg limit with ion traps

Sub-Planck phase-space structures in the Wigner function of the motional degree of freedom of a trapped ion can be used to perform weak force measurements with Heisenberg-limited sensitivity. We propose methods to engineer the Hamiltonian of the trapped ion to generate states with such small scale structures, and we show how to use them in quantum metrology applications.Comment: 10 pages, 6 figure

Quantum signatures of chaos in the dynamics of a trapped ion

We show how a nonlinear chaotic system, the parametrically kicked nonlinear oscillator, may be realised in the dynamics of a trapped, laser-cooled ion, interacting with a sequence of standing wave pulses. Unlike the original optical scheme [G.J.Milburn and C.A.Holmes, Phys. Rev A, 44, p4704, (1991)], the trapped ion enables strongly quantum dynamics with minimal dissipation. This should permit an experimental test of one of the quantum signatures of chaos; irregular collapse and revival dynamics of the average vibrational energy.Comment: 9 pages, 9 Postscript figures, Revtex, submitted to Phys. Rev.