947 research outputs found
Uso do clorofilômetro como indicador da necessidade de adubação nitrogenada em cobertura em arroz irrigado.
O objetivo deste estudo foi avaliar a influĂŞncia do manejo de N baseado no uso do clorofilĂ´metro no desempenho da cultivar BRS Tropical de arroz irrigado
Eficiência do método de desinfestação de explantes de Ilex paraguariensis Saint hilaire por cloreto de mercúrio.
EVINCI. Resumo 009
Generation of Entangled N-Photon States in a Two-Mode Jaynes-Cummings Model
We describe a mathematical solution for the generation of entangled N-photon
states in two field modes. A simple and compact solution is presented for a
two-mode Jaynes-Cummings model by combining the two field modes in a way that
only one of the two resulting quasi-modes enters in the interaction term. The
formalism developed is then applied to calculate various generation
probabilities analytically. We show that entanglement, starting from an initial
field and an atom in one defined state may be obtained in a single step. We
also show that entanglement may be built up in the case of an empty cavity and
excited atoms whose final states are detected, as well as in the case when the
final states of the initially excited atoms are not detected.Comment: v2: 5 pages, RevTeX4, minor text changes + 1 figure added, revised
version to be published in PRA, May 200
Obtenção e validação de descritores das cultivares de maracujazeiro silvestre BRS Pérola do Cerrado, BRS Céu do Cerrado e BRS Rosea Púrpura.
Shape-invariant quantum Hamiltonian with position-dependent effective mass through second order supersymmetry
Second order supersymmetric approach is taken to the system describing motion
of a quantum particle in a potential endowed with position-dependent effective
mass. It is shown that the intertwining relations between second order partner
Hamiltonians may be exploited to obtain a simple shape-invariant condition.
Indeed a novel relation between potential and mass functions is derived, which
leads to a class of exactly solvable model. As an illustration of our
procedure, two examples are given for which one obtains whole spectra
algebraically. Both shape-invariant potentials exhibit harmonic-oscillator-like
or singular-oscillator-like spectra depending on the values of the
shape-invariant parameter.Comment: 16 pages, 5 figs; Present e-mail of AG: [email protected]
A general scheme for the effective-mass Schrodinger equation and the generation of the associated potentials
A systematic procedure to study one-dimensional Schr\"odinger equation with a
position-dependent effective mass (PDEM) in the kinetic energy operator is
explored. The conventional free-particle problem reveals a new and interesting
situation in that, in the presence of a mass background, formation of bound
states is signalled. We also discuss coordinate-transformed, constant-mass
Schr\"odinger equation, its matching with the PDEM form and the consequent
decoupling of the ambiguity parameters. This provides a unified approach to
many exact results known in the literature, as well as to a lot of new ones.Comment: 16 pages + 1 figure; minor changes + new "free-particle" problem;
version published in Mod. Phys. Lett.
A generalized quantum nonlinear oscillator
We examine various generalizations, e.g. exactly solvable, quasi-exactly
solvable and non-Hermitian variants, of a quantum nonlinear oscillator. For all
these cases, the same mass function has been used and it has also been shown
that the new exactly solvable potentials possess shape invariance symmetry. The
solutions are obtained in terms of classical orthogonal polynomials
- …