Atom Field Interaction
Mostrando 13-24 de 25 artigos, teses e dissertações.
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13. O efeito Casimir dinâmico e decoerência
In this thesis we first demonstrate that the inevitable action of the environment can be substantially weakened when considering appropriate nonstationary quantum systems. Beyond protecting quantum states against decoherence, an oscillating frequency can be engineered to make the system-reservoir coupling almost negligible. Differently from the program for e
Publicado em: 2008
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14. Síntese de compostos com potenciais atividades biológicas ou magnéticas
This thesis is divided in two parts and presents the results of our studies on the synthesis and the study of biological or magnetic proprieties of a series of ligands and their transition metal complexes. Firstly we prepared a series of dithiacarboxilic acids and their metal complexes to investigate the biological activity of these compounds against fungi,
Publicado em: 2008
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15. Quantum entanglement between atoms located in distinct cavities / Emaranhamento quantico entre atomos localizados em cavidades distintas
In this work, we study the dynamics of the entanglement between two remote atoms in distinct cavities. The main focus is the production of maximal entangled states between identical atoms of two levels in distinct cavities and, in particular, coupled cavities. Initially we present the main concepts of the Theory of Quantum Information, qualitative and quanti
Publicado em: 2007
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16. Estado fundamental e excitações coletivas de condensados de Bose-Einstein espinoriais / Ground state and collective excitations od spinor Bose-Einstein condensates
In the framework of the Bogoliubov theory, we determined the equilibrium configurations and the collective excitations of a homogeneous Bose-Einstein S = 1 spinor condensate, in the presence and absence of an externa1 magnetic field. In this thesis we found the equilibrium configurations as function of the parameters and m, where q is the intensity of the qu
Publicado em: 2007
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17. On some classical and quantum effects due to gravitational fields
We consider the gravitational fields generated by a cosmic string, a global monopole and a tubular matter with interior magnetic field (Safko-Witten space-time), and examine some classical and quantum effects due to these fields. We investigate the Aharonov-Bohm effect in the space-time of a cosmic string, using the loop variables. In the space-time of a glo
Brazilian Journal of Physics. Publicado em: 2006-03
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18. Propriedades de termoluminescência, ressonância paramagnética eletrônica e absorção óptica da rodonita natural e sintética / Thermoluminescence, electron paramagnetic resonance and optical absorption properties of natural and synthetic Rodonita
The optical absorption, electron paramagnetic resonance and thermoluminescence properties of natural silicate mineral, rhodonite with chemical formula (Mn,Ca,Fe,Mg)SiO3 as well as synthetic samples pure or doped have been investigated. Synthetic samples were obtained heating appropriated mixture of oxides components of rhodonite to above melting temperature
Publicado em: 2005
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19. Transferencia de coerencia atomo-campo em um micromaser de dois fotons
The construction of pure states of the electromagnetic field is important not only for the study of the foundations of the quantum mechanics, such as the question of the Schrõdinger cat states, but also for its potential applications, for example, in quantum computation, quantum criptography and in higher precision measurements. In this thesis, we present t
Publicado em: 2003
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20. Relógio atômico a feixe efusivo de 133Cs: estudo da estabilidade e da acuracia como função do deslocamento da frequência atômica devido ao efeito zeeman de segunda ordem, ao cavity pulling e ao rabi pulling / A 133Cs Atomic Beam Clock: study of its accuracy and stability as a function of the atomic frequency shift due to the second order zeeman effect, the cavity pulling and the rabi pulling
Since 1967, the definition of the second is based on the atomic properties of the 133Cs atom. The device that realises this definition is an atomic clock. In this work, we present the progress made in the last year on Brazilian scientific time and frequency program. The aim of this dissertation work is the caracterization of our standard. We report the major
Publicado em: 2003
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21. Laser effects in semiconductor heterostructures within an extended dressed-atom approach
We extend the dressed-atom approach to treat the interaction of a laser field with a semiconductor system. The semiconductor is modeled via a simple Kane band-structure scheme and the interaction with the laser field is incorporate through the renormalization of the semiconductor energy gap and conduction/valence effective masses. Far from resonances, such o
Brazilian Journal of Physics. Publicado em: 2002-06
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22. Dinamica de sistemas quanticos : atomos em cavidades de ions aprisionados
In this thesis we studied the dynamics of two quantum systems: atoms in a cavity and trapped ions. For atoms in a cavity ( QED ) , we studied the dynamics of field prepared in a superposition of coherent states and a statistical mixture. In this system, using a Intensity-Dependence Jaynes-Cummings model (DNJCM) we discuss some aspects of the dynamics of atom
Publicado em: 2002
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23. Caracterização de uma armadilha magneto-optica para átomos de sódio em célula de vapor. / Characterization of a magneto-optical trap for sodium atoms in vapor cell.
Among the various atomic motion control techniques using radiation pressure magneto-optic trapping has been looked at with great enthusiasm because it produces samples of cold atoms (temperatures about μK), with high densities and confined in small regions of space. Due to these motivations the efforts for developing and characterizing these atoms traps
Publicado em: 1994
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24. Computation of Large Molecules with the Hartree-Fock Model
The usual way to compute Hartree-Fock type functions for molecules is by an expansion of the one-electron functions (molecular orbitals) in a linear combination of analytical functions (LCAO-MO-SCF, linear combination of atomic orbitals—Molecular Orbital—Self Consistent field). The expansion coefficients are obtained variationally. This technique require