1,182 research outputs found
The Ramanujan master theorem and its implications for special functions
We study a number of possible extensions of the Ramanujan master theorem,
which is formulated here by using methods of Umbral nature. We discuss the
implications of the procedure for the theory of special functions, like the
derivation of formulae concerning the integrals of products of families of
Bessel functions and the successive derivatives of Bessel type functions. We
stress also that the procedure we propose allows a unified treatment of many
problems appearing in applications, which can formally be reduced to the
evaluation of exponential- or Gaussian-like integrals.Comment: 12 page
Definite integrals and operational methods
An operatorial method, already employed to formulate a generalization of the
Ramanujan master theorem, is applied to the evaluation of integrals of various
type. This technique provide a very flexible and powerful tool yielding new
results encompassing various aspects of the special function theory.Comment: 9 pages; minor changes to match published versio
Operator solutions for fractional Fokker-Planck equations
We obtain exact results for fractional equations of Fokker-Planck type using
evolution operator method. We employ exact forms of one-sided Levy stable
distributions to generate a set of self-reproducing solutions. Explicit cases
are reported and studied for various fractional order of derivatives, different
initial conditions, and for different versions of Fokker-Planck operators.Comment: 4 pages, 3 figure
Generating random density matrices
We study various methods to generate ensembles of random density matrices of
a fixed size N, obtained by partial trace of pure states on composite systems.
Structured ensembles of random pure states, invariant with respect to local
unitary transformations are introduced. To analyze statistical properties of
quantum entanglement in bi-partite systems we analyze the distribution of
Schmidt coefficients of random pure states. Such a distribution is derived in
the case of a superposition of k random maximally entangled states. For another
ensemble, obtained by performing selective measurements in a maximally
entangled basis on a multi--partite system, we show that this distribution is
given by the Fuss-Catalan law and find the average entanglement entropy. A more
general class of structured ensembles proposed, containing also the case of
Bures, forms an extension of the standard ensemble of structureless random pure
states, described asymptotically, as N \to \infty, by the Marchenko-Pastur
distribution.Comment: 13 pages in latex with 8 figures include
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