3,533 research outputs found
Comportamento da cultivar de tomate Rio Grande, na regiao de Teresina.
No mercado piauiense, o tomate (Lycopersicum esculentum Mill.) e o principal produto olericola, de maior volume e valor comercializado. Entretanto, o Estado do Piaui nao apresenta posicao destacada como produtor dessa hortalica. A cultivar Rio Grande apresentou a grande vantagem de frutos resistentes ao rachamento, com baixo indice de ocorrencia da podridao apical, de coloracao vermelho intensa, tanto interna como externamente, o que lhes confere boa aceitacao comercial. Seu cultivo mostra-se vantajoso, quando comparado as plantas de crescimento indeterminado, pois as plantas nao exigem desbrota, bastando-lhes dois amarrios e tutores de menor tamanho. Como consequencia e menor a necessidade de mao-de-obra e de material, reduzindo consideravelmente seus custos de producao.bitstream/item/95920/1/CT310001.pd
Dynamics of two atoms coupled to a cavity field
We investigate the interaction of two two-level atoms with a single mode
cavity field. One of the atoms is exactly at resonance with the field, while
the other is well far from resonance and hence is treated in the dispersive
limit. We find that the presence of the non-resonant atom produces a shift in
the Rabi frequency of the resonant atom, as if it was detuned from the field.
We focus on the discussion of the evolution of the state purity of each atom.Comment: LaTex, 2 figure
Phase space tweezers for tailoring cavity fields by quantum Zeno dynamics
We discuss an implementation of Quantum Zeno Dynamics in a Cavity Quantum
Electrodynamics experiment. By performing repeated unitary operations on atoms
coupled to the field, we restrict the field evolution in chosen subspaces of
the total Hilbert space. This procedure leads to promising methods for
tailoring non-classical states. We propose to realize `tweezers' picking a
coherent field at a point in phase space and moving it towards an arbitrary
final position without affecting other non-overlapping coherent components.
These effects could be observed with a state-of-the-art apparatus
Self-assembly of iron nanoclusters on the Fe3O4(111) superstructured surface
We report on the self-organized growth of a regular array of Fe nanoclusters
on a nanopatterned magnetite surface. Under oxidizing preparation conditions
the (111) surface of magnetite exhibits a regular superstructure with
three-fold symmetry and a 42 A periodicity. This superstructure represents an
oxygen terminated (111) surface, which is reconstructed to form a periodically
strained surface. This strain patterned surface has been used as a template for
the growth of an ultrathin metal film. A Fe film of 0.5 A thickness was
deposited on the substrate at room temperature. Fe nanoclusters are formed on
top of the surface superstructure creating a regular array with the period of
the superstructure. We also demonstrate that at least the initial stage of Fe
growth occurs in two-dimensional mode. In the areas of the surface where the
strain pattern is not formed, random nucleation of Fe was observed.Comment: 6 pages, 3 figure
Atomistic mechanisms for the ordered growth of Co nano-dots on Au(788): comparison of VT-STM experiments and multi-scaled calculations
Hetero-epitaxial growth on a strain-relief vicinal patterned substrate has
revealed unprecedented 2D long range ordered growth of uniform cobalt
nanostructures. The morphology of a Co sub-monolayer deposit on a Au(111)
reconstructed vicinal surface is analyzed by Variable Temperature Scanning
Tunneling Microscopy (VT-STM) experiments. A rectangular array of nano-dots
(3.8 nm x 7.2 nm) is found for a particularly large deposit temperature range
lying from 60 K to 300 K. Although the nanodot lattice is stable at room
temperature, this paper focus on the early stage of ordered nucleation and
growth at temperatures between 35 K and 480 K. The atomistic mechanisms leading
to the nanodots array are elucidated by comparing statistical analysis of
VT-STM images with multi-scaled numerical calculations combining both Molecular
Dynamics for the quantitative determination of the activation energies for the
atomic motion and the Kinetic Monte Carlo method for the simulations of the
mesoscopic time and scale evolution of the Co submonolayer
Process tomography of field damping and measurement of Fock state lifetimes by quantum non-demolition photon counting in a cavity
The relaxation of a quantum field stored in a high- superconducting cavity
is monitored by non-resonant Rydberg atoms. The field, subjected to repetitive
quantum non-demolition (QND) photon counting, undergoes jumps between photon
number states. We select ensembles of field realizations evolving from a given
Fock state and reconstruct the subsequent evolution of their photon number
distributions. We realize in this way a tomography of the photon number
relaxation process yielding all the jump rates between Fock states. The damping
rates of the photon states () are found to increase
linearly with . The results are in excellent agreement with theory including
a small thermal contribution
Generating and probing a two-photon Fock state with a single atom in a cavity
A two-photon Fock state is prepared in a cavity sustaining a "source mode "
and a "target mode", with a single circular Rydberg atom. In a third-order
Raman process, the atom emits a photon in the target while scattering one
photon from the source into the target. The final two-photon state is probed by
measuring by Ramsey interferometry the cavity light shifts induced by the
target field on the same atom. Extensions to other multi-photon processes and
to a new type of micromaser are briefly discussed
A path integral for classical dynamics, entanglement, and Jaynes-Cummings model at the quantum-classical divide
The Liouville equation differs from the von Neumann equation 'only' by a
characteristic superoperator. We demonstrate this for Hamiltonian dynamics, in
general, and for the Jaynes-Cummings model, in particular. -- Employing
superspace (instead of Hilbert space), we describe time evolution of density
matrices in terms of path integrals which are formally identical for quantum
and classical mechanics. They only differ by the interaction contributing to
the action. This allows to import tools developed for Feynman path integrals,
in order to deal with superoperators instead of quantum mechanical commutators
in real time evolution. Perturbation theory is derived. Besides applications in
classical statistical physics, the "classical path integral" and the parallel
study of classical and quantum evolution indicate new aspects of (dynamically
assisted) entanglement (generation). Our findings suggest to distinguish
'intra'- from 'inter-space' entanglement.Comment: 22 pages; based on invited talk at Quantum 2010 - Advances in
Foundations of Quantum mechanics and Quantum Information with Atoms and
Photons (Torino, May 2010). To appear in Int. J. Qu. Inf
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