Excitonic entanglement of protected states in quantum dot molecules

The entanglement of an optically generated electron-hole pair in artificial quantum dot molecules is calculated considering the effects of decoherence by interaction with environment. Since the system evolves into a mixed states and due to the complexity of energy level structure, we use the negativity as entanglement quantifier, which is well defined in $d \otimes d^\prime$ composite vector spaces. By a numerical analysis of the non-unitary dynamics of the exciton states, we establish the feasibility of producing protected entangled superpositions by an appropriate tuning of bias electric field, $F$. A stationary state with a high value of negativity (high degree of entanglement) is obtained by fine tuning of $F$ close to a resonant condition between indirect excitons. We also found that when the optical excitation is set approximately equal to the electron tunneling coupling, $\Omega/T_e \sim 1$, the entanglement reaches a maximum value. In front of the experimental feasibility of the specific condition mentioned before, our proposal becomes an useful strategy to find robust entangled states in condensed matter systems.Comment: 4 figure

Alterations in brain connectivity due to plasticity and synaptic delay

Brain plasticity refers to brain's ability to change neuronal connections, as a result of environmental stimuli, new experiences, or damage. In this work, we study the effects of the synaptic delay on both the coupling strengths and synchronisation in a neuronal network with synaptic plasticity. We build a network of Hodgkin-Huxley neurons, where the plasticity is given by the Hebbian rules. We verify that without time delay the excitatory synapses became stronger from the high frequency to low frequency neurons and the inhibitory synapses increases in the opposite way, when the delay is increased the network presents a non-trivial topology. Regarding the synchronisation, only for small values of the synaptic delay this phenomenon is observed

Field sources in a Lorentz symmetry breaking scenario with a single background vector

This paper is devoted to investigating the interactions between stationary sources of the electromagnetic field, in a model which exhibits explicit Lorentz-symmetry breaking due to the presence of a single background vector. We focus on physical phenomena that emerge from this kind of breaking and which have no counterpart in Maxwell Electrodynamics

Diagnose foliar na cultura da banana.

A maioria das espécies de bananeira (Musa spp.) originou-se do Continente Asiático. Na evolução das bananeiras comestíveis, participaram, principalmente, as espécies selvagens Musa acuminata Colla eM balbisiana Colla, de modo que cada variedade contém combinações variadas de genomas (A e B) completos dessas espécies (DANTAS et al., 1999b). As variedades de banana mais difundidas no Brasil são as triploides AAB do tipo Prata (Prata, Pacovan e Prata-Anã), do tipo Terra (Terra, Terrinha e D' Angola), a Maçã e a Thap Maeo; e as triploides AAA, denominadas banana D'Água ou Caturra (Nanica, Nanicão, Grande Naine e Williams), bem como a Caipira e aNamoHá ainda, no mercado, uma série de novas variedades tetraploides AAAB, como: Tropical, Fhia-Maravilha, Preciosa, Prata-Caprichosa, Prata-Garantida, Japira e Vitória

Balanço da 7ª Jornada Científica da Embrapa Mandioca e Fruticultura.

No período de 14 a 16 de agosto de 2013 no auditório I da Embrapa Mandioca e Fruticultura foi realizada a 7a Jornada Científica da Unidade. O evento contou com a apresentação de 89 trabalhos, correspondendo a 90% do total de 99 que foi submetido ao Comitê Local de Publicações (CLP). Daqueles trabalhos, 56 foram apresentados oralmente e 33 na forma de pôsteres (Figura 1), tendo a participação de 44 pesquisadores orientadores e um analista orientador

Field sources in a CPT-even Lorentz-violation Maxwell electrodynamics

This paper is dedicated to the study of interactions between external sources for the electromagnetic field in a model which exhibits Lorentz symmetry breaking. We investigate such interactions in the CPT-even photon sector of the Standard Model Extension (SME), where the Lorentz symmetry breaking is caused by a background tensor $K_{(F)\alpha\beta\sigma\tau}$. Since the background tensor is very tiny, we treat it perturbatively up to first order and we focus on physical phenomena which have no counterpart in Maxwell electrodynamics. We consider effects related to field sources describing point-like charges, straight line currents and Dirac strings. We also investigate the so called Aharonov-Bohm bound states in a Lorentz-symmetry breaking scenario. We use atomic experimental data to verify if we could impose upper bounds to the Lorentz-symmetry breaking parameters involved. We also use some overestimated constrains for the Lorentz-symmetry breaking parameters in order to investigate if the obtained results could be relevant for condensed matter systems.Comment: 12 page