1,846 research outputs found

    Optical Properties of Crystals with Spatial Dispersion: Josephson Plasma Resonance in Layered Superconductors

    Full text link
    We derive the transmission coefficient, T(ω)T(\omega), for grazing incidence of crystals with spatial dispersion accounting for the excitation of multiple modes with different wave vectors k{\bf k} for a given frequency ω\omega. The generalization of the Fresnel formulas contains the refraction indices of these modes as determined by the dielectric function ϵ(ω,k)\epsilon(\omega,{\bf k}). Near frequencies ωe\omega_e, where the group velocity vanishes, T(ω)T(\omega) depends also on an additional parameter determined by the crystal microstructure. The transmission TT is significantly suppressed, if one of the excited modes is decaying into the crystal. We derive these features microscopically for the Josephson plasma resonance in layered superconductors.Comment: 4 pages, 2 figures, epl.cls style file, minor change

    Decoherence and Entanglement Dynamics in Fluctuating Fields

    Full text link
    We study pure phase damping of two qubits due to fluctuating fields. As frequently employed, decoherence is thus described in terms of random unitary (RU) dynamics, i.e., a convex mixture of unitary transformations. Based on a separation of the dynamics into an average Hamiltonian and a noise channel, we are able to analytically determine the evolution of both entanglement and purity. This enables us to characterize the dynamics in a concurrence-purity (CP) diagram: we find that RU phase damping dynamics sets constraints on accessible regions in the CP plane. We show that initial state and dynamics contribute to final entanglement independently.Comment: 10 pages, 5 figures, added minor changes in order to match published versio

    Caracterização da composição química de pera "Abate Fetel" e "William's" em três estádios de maturação.

    Get PDF
    Editores técnicos: Marcílio José Thomazini, Elenice Fritzsons, Patrícia Raquel Silva, Guilherme Schnell e Schuhli, Denise Jeton Cardoso, Luziane Franciscon. EVINCI. Resumos
    corecore