403,651 research outputs found

    Singular lagrangian systems and variational constrained mechanics on Lie algebroids

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    The purpose of this paper is describe Lagrangian Mechanics for constrained systems on Lie algebroids, a natural framework which covers a wide range of situations (systems on Lie groups, quotients by the action of a Lie group, standard tangent bundles...). In particular, we are interested in two cases: singular Lagrangian systems and vakonomic mechanics (variational constrained mechanics). Several examples illustrate the interest of these developments.Comment: 42 pages, Section with examples improve

    Wave polarizations for a beam-like gravitational wave in quadratic curvature gravity

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    We compute analytically the tidal field and polarizations of an exact gravitational wave generated by a cylindrical beam of null matter of finite width and length in quadratic curvature gravity. We propose that this wave can represent the gravitational wave that keep up with the high energy photons produced in a gamma ray burst (GRB) source.Comment: 5 pages, 3 figures, minor corrections, to appear in CQ

    A new geometric setting for classical field theories

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    A new geometrical setting for classical field theories is introduced. This description is strongly inspired in the one due to Skinner and Rusk for singular lagrangians systems. For a singular field theory a constraint algorithm is developed that gives a final constraint submanifold where a well-defined dynamics exists. The main advantage of this algorithm is that the second order condition is automatically included.Comment: 22 page

    Complex analytic realizations for quantum algebras

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    A method for obtaining complex analytic realizations for a class of deformed algebras based on their respective deformation mappings and their ordinary coherent states is introduced. Explicit results of such realizations are provided for the cases of the qq-oscillators (qq-Weyl-Heisenberg algebra) and for the suq(2)su_{q}(2) and suq(1,1)su_{q}(1,1) algebras and their co-products. They are given in terms of a series in powers of ordinary derivative operators which act on the Bargmann-Hilbert space of functions endowed with the usual integration measure. In the q→1q\rightarrow 1 limit these realizations reduce to the usual analytic Bargmann realizations for the three algebras.Comment: 18 page

    Fast gates for ion traps by splitting laser pulses

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    We present a fast phase gate scheme that is experimentally achievable and has an operation time more than two orders of magnitude faster than current experimental schemes for low numbers of pulses. The gate time improves with the number of pulses following an inverse power law. Unlike implemented schemes which excite precise motional sidebands, thus limiting the gate timescale, our scheme excites multiple motional states using discrete ultra-fast pulses.We use beam-splitters to divide pulses into smaller components to overcome limitations due to the finite laser pulse repetition rate. This provides gate times faster than proposed theoretical schemes when we optimize a practical setup
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