937 research outputs found

    Deterministic Transformations of Multipartite Entangled States with Tensor Rank 2

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    Transformations involving only local operations assisted with classical communication are investigated for multipartite entangled pure states having tensor rank 2. All necessary and sufficient conditions for the possibility of deterministically converting truly multipartite, rank-2 states into each other are given. Furthermore, a chain of local operations that successfully achieves the transformation has been identified for all allowed transformations. The identified chains have two nice features: (1) each party needs to carry out at most one local operation and (2) all of these local operations are also deterministic transformations by themselves. Finally, it is found that there are disjoint classes of states, all of which can be identified by a single real parameter, which remain invariant under deterministic transformations.Comment: 27 pages, 1 figure; added new references and improved the presentatio

    Carrier-induced refractive index change and optical absorption in wurtzite InN and GaN: Fullband approach

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    Based on the full band electronic structure calculations, first we consider the effect of n-type doping on the optical absorption and the refractive index in wurtzite InN and GaN. We identify quite different dielectric response in either case; while InN shows a significant shift in the absorption edge due to n-type doping, this is masked for GaN due to efficient cancellation of the Burstein-Moss effect by the band gap renormalization. For high doping levels the intraband absorption becomes significant in InN. Furthermore, we observe that the free-carrier plasma contribution to refractive index change becomes more important than both band filling and the band gap renormalization for electron densities above 1019^{19}~cm3^{-3} in GaN, and 1020^{20}~cm3^{-3} in InN. As a result of the two different characteristics mentioned above, the overall change in the refractive index due to n-type doping is much higher in InN compared to GaN, which in the former exceeds 4\% for a doping of 1019^{19}~cm3^{-3} at 1.55~μ\mum wavelength. Finally, we consider intrinsic InN under strong photoexcitation which introduces equal density of electron and holes thermalized to their respective band edges. The change in the refractive index at 1.55~μ\mum is observed to be similar to the n-doped case up to a carrier density of 1020^{20}~cm3^{-3}. However, in the photoexcited case this is now accompanied by a strong absorption in this wavelength region due to Γ5vΓ6v\Gamma^v_5 \to \Gamma^v_6 intravalence band transition. Our findings suggest that the alloy composition of Inx_xGa1x_{1-x}N can be optimized in the indium-rich region so as to benefit from high carrier-induced refractive index change while operating in the transparency region to minimize the losses. These can have direct implications for InN-containing optical phase modulators and lasers.Comment: Revised with an appendix, two additional figures, and more discussions; 10 pages, 14 figures; published versio

    The optimization of voltage parameter for tissue electroporation in somatic embryos of Astragalus chrysochlorus (Leguminosae)

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    Somatic embryo tissues of Astragalus chrysochlorus were transformed with the b-glucuronidase (GUS) and neomycin phosphotransferase II (npt II) genes by electroporation. The effect of electric field strength was tested for transient expression. It was found that 1000 V/cm and 200 ms and 1 pulse wasthe optimum combination to transform embryo tissues (expression level was 61.5%). Electroporated somatic embryo tissues were positive for GUS expression and PCR analysis for the genes GUS and npt II. After PCR analysis, we found that the efficiency of the somatic embryos with transient GUS expression by electroporation was 48%

    Gauge covariance and spin-current conservation in the gauge-field formulation of systems with spin–orbit coupling

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    The question of gauge covariance in the non-Abelian gauge-field formulation of two space-dimensional systems with spin-orbit coupling relevant to spintronics is investigated. Although these are generally gauge-fixed models, it is found that for the class of gauge fields that are spacetime independent and satisfy a U(1) algebra, thus having a vanishing field strength, there is a residual gauge freedom in the Hamiltonian. The gauge transformations assume the form of a space-dependent rotation of the transformed wavefunctions with rotation angles and axes determined by the specific form of the gauge field, i.e. the spin-orbit coupling. The fields can be gauged away, reducing the Hamiltonian to one which is isospectral to the free-particle Hamiltonian, and giving rise to the phenomenon of persistent spin helix reported first by Bernevig et al (2006 Phys. Rev. Lett. 97 236601). The investigation of the global gauge transformations leads to the derivation of a continuity equation where the component of the spin density along given directions, again fixed by the specific form of the gauge field, is conserved

    Drying kinetic and physical properties of green laird lentil (Lens culinaris) in microwave drying

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    The objective of this study was to study the drying kinetics of green laird lentil (Lens culinaris) in microwave drying method. The drying data were fitted to the various thin-layer models. All the models were compared using three statistical parameters, that is, coefficient of determination R2, reduced mean square of the deviation X2 and root means square error RMSE. Also, the lentil’s physical and mechanical features crude protein, oil and ash parameters were specified under different microwave levels. It was concluded according to these values that the recommended model is the best model, which can define the drying curves at the practices at 300, 400, 550, 700 and 800 W in drying lentil by microwave.Key words: Microwave, lentil, physical properties, crude protein, drying

    Hadron Production in Neutrino-Nucleon Interactions at High Energies

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    The multi-particle production at high energy neutrino- nucleon collisions are investigated through the analysis of the data of the experiment CERN-WA-025 at neutrino energy less than 260GeV and the experiments FNAL-616 and FNAL-701 at energy range 120-250 GeV. The general features of these experiments are used as base to build a hypothetical model that views the reaction by a Feynman diagram of two vertices. The first of which concerns the weak interaction between the neutrino and the quark constituents of the nucleon. At the second vertex, a strong color field is assumed to play the role of particle production, which depend on the momentum transferred from the first vertex. The wave function of the nucleon quarks are determined using the variation method and relevant boundary conditions are applied to calculate the deep inelastic cross sections of the virtual diagram.Comment: 6 pages PDF forma
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