Spin-orbit mode transfer via a classical analog of quantum teleportation

We translate the quantum teleportation protocol into a sequence of coherent operations involving three degrees of freedom of a classical laser beam. The protocol, which we demonstrate experimentally, transfers the polarisation state of the input beam to the transverse mode of the output beam. The role of quantum entanglement is played by a non-separable mode describing the path and transverse degrees of freedom. Our protocol illustrates the possibility of new optical applications based on this intriguing classical analogue of quantum entanglement.Comment: 5 pages, 7 figure

Tripartite entanglement and quantum relative entropy

We establish relations between tripartite pure state entanglement and additivity properties of the bipartite relative entropy of entanglement. Our results pertain to the asymptotic limit of local manipulations on a large number of copies of the state. We show that additivity of the relative entropy would imply that there are at least two inequivalent types of asymptotic tripartite entanglement. The methods used include the application of some useful lemmas that enable us to analytically calculate the relative entropy for some classes of bipartite states.Comment: 7 pages, revtex, no figures. v2: discussion about recent results, 2 refs. added. Published versio

A Quantum solution to the Byzantine agreement problem

We present a solution to an old and timely problem in distributed computing. Like Quantum Key Distribution (QKD), quantum channels make it possible to achieve taks classically impossible. However, unlike QKD, here the goal is not secrecy but agreement, and the adversary is not outside but inside the game, and the resources require qutrits.Comment: 4 pages, 1 figur

Caracterização biométrica e físico-química dos frutos de acessos de manga 'Ubá'.

Este trabalho teve como objetivo avaliar a dissimilaridade genética de acessos de manga ?Ubá? na região leste de Minas Gerais, por meio da caracterização biométrica e físico-química dos frutos, visando a identificar materiais de interesse industrial para futuros trabalhos de melhoramento. Frutos de 67 acessos de mangueira Ubá provenientes do leste de Minas Gerais foram caracterizados, avaliando-se: massa da fruta, massa do endocarpo, relação polpa/endocarpo, diâmetro longitudinal, diâmetro transversal, sólidos solúveis totais, acidez total titulável, relação sólidos solúveis total/acidez total titulável e pH. Os resultados foram avaliados por estatística descritiva, utilizando-se de medida de tendência central (média) e de variabilidade de dados (desvio-padrão). Foram realizadas análises estatísticas, utilizando-se das técnicas de agrupamento e medidas de dissimilaridade. Os frutos que apresentaram melhores características para o processamento foram os provenientes dos acessos 10; 22; 23; 24; 35; 38; 40; 42; 52; 55 e 63. A análise de agrupamento mostrou a formação de dois grupos de acessos com base nas características biométricas e físico-químicas dos frutos, o que demonstra variabilidade genética em mangueiras Ubá, no leste de Minas Gerais

Electric field inversion asymmetry: Rashba and Stark effects for holes in resonant tunneling devices

We report experimental evidence of excitonic spin-splitting, in addition to the conventional Zeeman effect, produced by a combination of the Rashba spin-orbit interaction, Stark shift and charge screening. The electric-field-induced modulation of the spin-splitting are studied during the charging and discharging processes of p-type GaAs/AlAs double barrier resonant tunneling diodes (RTD) under applied bias and magnetic field. The abrupt changes in the photoluminescence, with the applied bias, provide information of the charge accumulation effects on the device.Comment: 4 pages, 2 figure

Conversion of descriptor representations to state-space form: an extension of the shuffle algorithm

This paper proposes a systematic procedure for the determination of state-space models from an available descriptor representation of a linear dynamic system. The goal is to determine a state equation, a set of algebraic equations and an output equation in terms of the state and input variables. It is shown that standard methods may fail to convert the descriptor representation to state-space form, even for simple electrical circuit models obtained from Kirchoff’s laws and constitutive element equations. A novel procedure to address this problem is then proposed as an extension of the classic shuffle algorithm combined with a singular value decomposition approach. In addition to an illustrative example involving a simple electrical circuit, the proposed method is employed in a case study involving the modeling of three-dimensional RLC networks with a large number of components

Entanglement measure for general pure multipartite quantum states

We propose an explicit formula for an entanglement measure of pure multipartite quantum states, then study a general pure tripartite state in detail, and at end we give some simple but illustrative examples on four-qubits and m-qubits states.Comment: 5 page

Supressão de plantas daninhas por leguminosas consorciadas com cupuaçuzeiro na Amazônia Central.

O objetivo deste trabalho foi avaliar o efeito de leguminosas de cobertura consorciadas com cupuaçuzeiro na supressão de plantas daninhas. O experimento foi conduzido no campo experimental da Embrapa Amazônia Ocidental