1,705 research outputs found
Multi-Periodic Coherent States and the WKB-Exactness
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''
We show that the WKB approximation gives the exact result in the trace
formula of ``'', which is the non-compact counterpart of , in terms
of the ``multi-periodic'' coherent state. We revisit the symplectic 2-forms on
and and, especially, construct that on 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
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 71 mcm and
3 V/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 Mn and Mn ions.Comment: 4 pages, 4 eps figures, to be published in J. Appl. Phy
Exchange Gate on the Qudit Space and Fock Space
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
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)
We prepared polycrystalline samples of RPdO (R = La, Nd, Sm and Gd)
using a NaCl-flux technique. The measured resistivity is of the order of
10 cm 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 NdCePdO, 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 cm/Vs is much lower than a typical value of 1-10 cm/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
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
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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