1,705 research outputs found

    Multi-Periodic Coherent States and the WKB-Exactness

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    We construct the path integral formula in terms of ``multi-periodic'' coherent state as an extension of the Nielsen-Rohrlich formula for spin. We make an exact calculation of the formula and show that, when a parameter corresponding to the magnitude of spin becomes large, the leading order term of the expansion coincides with the exact result. We also give an explicit correspondence between the trace formula in the multi-periodic coherent state and the one in the ``generalized'' coherent state.Comment: 28 pages, late

    Multi-Periodic Coherent States and the WKB-Exactness II ``Non-compact Case and Classical theories Revisited''

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    We show that the WKB approximation gives the exact result in the trace formula of ``CQNCQ^N'', which is the non-compact counterpart of CPNCP^N, in terms of the ``multi-periodic'' coherent state. We revisit the symplectic 2-forms on CPNCP^N and CQNCQ^N and, especially, construct that on CQNCQ^N with the unitary form. We also revisit the exact calculation of the classical patition functions of them.Comment: LaTeX, 29 page

    Universal charge transport of the Mn oxides in the high temperature limit

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    We have found that various Mn oxides have the universal resistivity and thermopower in the high temperature limit. The resistivities and thermopowers of all the samples go toward constant values of 7±\pm1 mΩ\Omegacm and −79±-79\pm3 μ\muV/K, which are independent of carrier density and crystal structures. We propose that the electric conduction occurs in a highly localized way in the high temperature limit, where the exchange of entropy and charge occurs in the neighboring Mn3+^{3+} and Mn4+^{4+} ions.Comment: 4 pages, 4 eps figures, to be published in J. Appl. Phy

    Exchange Gate on the Qudit Space and Fock Space

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    We construct the exchange gate with small elementary gates on the space of qudits, which consist of three controlled shift gates and three "reverse" gates. This is a natural extension of the qubit case. We also consider a similar subject on the Fock space, but in this case we meet with some different situation. However we can construct the exchange gate by making use of generalized coherent operator based on the Lie algebra su(2) which is a well--known method in Quantum Optics. We moreover make a brief comment on "imperfect clone".Comment: Latex File, 12 pages. I could solve the problems in Sec. 3 in the preceding manuscript, so many corrections including the title were mad

    SBML models and MathSBML

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    MathSBML is an open-source, freely-downloadable Mathematica package that facilitates working with Systems Biology Markup Language (SBML) models. SBML is a toolneutral,computer-readable format for representing models of biochemical reaction networks, applicable to metabolic networks, cell-signaling pathways, genomic regulatory networks, and other modeling problems in systems biology that is widely supported by the systems biology community. SBML is based on XML, a standard medium for representing and transporting data that is widely supported on the internet as well as in computational biology and bioinformatics. Because SBML is tool-independent, it enables model transportability, reuse, publication and survival. In addition to MathSBML, a number of other tools that support SBML model examination and manipulation are provided on the sbml.org website, including libSBML, a C/C++ library for reading SBML models; an SBML Toolbox for MatLab; file conversion programs; an SBML model validator and visualizer; and SBML specifications and schemas. MathSBML enables SBML file import to and export from Mathematica as well as providing an API for model manipulation and simulation

    Thermoelectric properties of the layered Pd oxide R_2PdO_4 (R = La, Nd, Sm and Gd)

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    We prepared polycrystalline samples of R2_2PdO4_4 (R = La, Nd, Sm and Gd) using a NaCl-flux technique. The measured resistivity is of the order of 103−104^3-10^4 Ω\Omegacm at room temperature, which is two orders of magnitude smaller than the values reported so far. We further studied the substitution effects of Ce for Nd in Nd1.9_{1.9}Ce0.1_{0.1}PdO4_4, where the substituted Ce decreases the resistivity and the magnitude of the thermopower. The activation energy gap of 70-80 meV and the effective mass of 15 evaluated from the measured data are suitable for thermoelectric materials, but the mobility of 10−6^{-6} cm2^2/Vs is much lower than a typical value of 1-10 cm2^2/Vs for other thermoelectric oxides.Comment: 5 pages, 5 figures, to appear in J. Phys. Soc. Jp

    Temperature dependence of the charge carrier mobility in gated quasi-one-dimensional systems

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    The many-body Monte Carlo method is used to evaluate the frequency dependent conductivity and the average mobility of a system of hopping charges, electronic or ionic on a one-dimensional chain or channel of finite length. Two cases are considered: the chain is connected to electrodes and in the other case the chain is confined giving zero dc conduction. The concentration of charge is varied using a gate electrode. At low temperatures and with the presence of an injection barrier, the mobility is an oscillatory function of density. This is due to the phenomenon of charge density pinning. Mobility changes occur due to the co-operative pinning and unpinning of the distribution. At high temperatures, we find that the electron-electron interaction reduces the mobility monotonically with density, but perhaps not as much as one might intuitively expect because the path summation favour the in-phase contributions to the mobility, i.e. the sequential paths in which the carriers have to wait for the one in front to exit and so on. The carrier interactions produce a frequency dependent mobility which is of the same order as the change in the dc mobility with density, i.e. it is a comparably weak effect. However, when combined with an injection barrier or intrinsic disorder, the interactions reduce the free volume and amplify disorder by making it non-local and this can explain the too early onset of frequency dependence in the conductivity of some high mobility quasi-one-dimensional organic materials.Comment: 9 pages, 8 figures, to be published in Physical Review

    Novel liquid crystalline organic semiconducting oligomers incorporating N-heterocyclic carbazole moieties for fluorescent OLEDs

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    A novel class of nematic liquid crystalline organic semiconducting oligomers incorporating N-heterocyclic carbazole moieties has been synthesised using simple and highly efficient reaction pathways. The electroluminescent colour of these novel oligomers can be varied in a controlled manner by molecular design. The values of the ionization potential and the electron affinity of these electroluminescent oligomers can also be matched by structural design to the HOMO energy level of the electron-blocking layer and the LUMO energy level of electron-transporting layer in the OLEDs to create low charge-injection barriers for electrons and holes, respectively leading to electroluminescence with an efficacy up to 4.1 cd A-1
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