1,930 research outputs found
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
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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
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