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Journals and Conferences
In this work we extend the sequential niching technique of Beasley et at. for multiple optimal determination, incorporating a local search to improve accuracy. In the proposed method a sequence of GA runs make use of a derating function and of niching and clearing techniques to promote the occupation of different niches in the function to be optimized. The… (More)
In this expression â† and â denote the creation and annihilation operators of the one-mode radiation field of frequency Ω, ωA the separation between the atomic levels, Ĵz denotes a collective atomic operator which counts the difference of population between the two atomic levels, Ĵ+ a collective atomic operator which promotes atoms from the lower level to… (More)
A symmetry of the parameter space of interacting boson models IBM-1 and IBM-2 is studied. The symmetry is associated with linear canonical transformations of boson operators, or, equivalently, with the existence of different realizations of the symmetry algebras of the models. The relevance of the parameter symmetry to physical observables is discussed.
Some properties of Plebański squeezing operator and squeezed states created with time-dependent quadratic in position and momentum Hamiltonians are reviewed. New type of tomography of quantum states called squeeze tomography is discussed.
An algebraic procedure to find extremal density matrices for any Hamiltonian of a qudit system is established. The extremal density matrices for pure states provide a complete description of the system, that is, the energy spectra of the Hamiltonian and their corresponding projectors. For extremal density matrices representing mixed states, one gets mean… (More)
It is shown that linear time-dependent invariants for arbitrary multidimensional quadratic systems can be obtained from the Lagrangian and Hamiltonian formulation procedures by considering a variation of coordinates and momenta that follows the classical trajectory and defines a noetherian symmetry transformation. ∗ Work supported in part by project… (More)
A two-dimensional generalized oscillator with time-dependent parameters is considered to study the two-mode squeezing phenomena. Specific choices of the parameters are used to determine the dispersion matrix and analytic expressions, in terms of standard hermite polynomials, of the wavefunctions and photon distributions.
The time dependent-integrals of motion, linear in position and momentum operators, of a quantum system are extracted from Noether’s theorem prescription by means of special time-dependent variations of coordinates. For the stationary case of the generalized two-dimensional harmonic oscillator, the time-independent integrals of motion are shown to correspond… (More)
The 2ν ββ decay half-lives of six nuclei, whose decays were previously reported as theoretically forbidden, are calculated by including the pairing interaction, which mixes different occupations and opens up the possibility of the decay. All allowed channels for the 0ν ββ decay are also computed. The estimated 2ν ββ half-lives suggest that measurements in… (More)