Quantum Points
Mostrando 13-24 de 33 artigos, teses e dissertações.
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13. Calculating the dimension of a Euclidian Quantum Gravity model / Cálculo da dimensão em um modelo de gravitação quântica euclidiana
This work had the intention of calculating the dimension of a Euclidian Quantum Gravity model which in based on the formalism of non commutative geometry. This work is a continuation of the article [4]. From [4] we know that using a commutative spectral triple allows us to generalize and treat ordinary geometry in a purely algebraic manner. From Non commutat
Publicado em: 2007
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14. Vibrational and electronic spectroscopy of diaminoanthraquinones as microenvironment probes / Espectroscopia vibracional e eletrônica de Diaminoantraquinonas como sondas de microambientes
In the present work, the ionochromic and solvatochromic behavior of several diaminoantraquinones were investigated by means of optical and vibrational spectroscopies, alongside computational simulation. The UV-Vis spectra of 1,2- diaminoantraquinone (1,2-DAAQ) were analyzed using empirical solvatochromic scales, like the Kamlet-Taft. Such analysis enabled an
Publicado em: 2007
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15. Hydrogenic impurity in ridge quantum wire
The binding energies as well as wave functions of hydrogenic impurities located in V-groove GaAs/Al xGa1-xAs quantum wires are calculated for different positions of the impurity inside the wires. The variational method is used and the carrier ground states are analytically calculated by an effective potential scheme together with a suitable coordinate transf
Brazilian Journal of Physics. Publicado em: 2006-12
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16. Estudo de fenomenos opticos ultra-rapidos lineares e não-lineares em pontos quanticos semicondutores / Study of ultrafast linear and nonlinear optical properties of semiconductor quantum dots
Nesta tese as propriedades ópticas lineares e não-lineares em pontos quânticos de semicondutores de band-gap diretos, CdTe e CdSe, são estudados em escala temporal de femtossegundos, especialmente aquelas propriedades importantes para aplicações em chaveamento totalmente óptico, como o tempo de resposta e a susceptibilidade de terceira ordem. Os proce
Publicado em: 2006
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17. Higher derivative quantum gravity near four dimensions
We investigate the role of the Gauss-Bonnet term for the n = 4 and n = 4-e renormalization group, for both conformal and general versions of the theory. The cancellation of the quantum effects of the Gauss-Bonnet term in the n = 4 limit represents an efficient test for the correctness of previous calculations and also resolves two long-standing problems conc
Brazilian Journal of Physics. Publicado em: 2005-12
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18. Dark energy in the universe, the irreversibility of time and neutrinos
In this review, I discuss briefly how the presence of a cosmological constant in the Universe may imply a decoherent evolution of quantum matter in it, and as a consequence a fundamental irreversibility of time unrelated in principle to CP properties (Cosmological CPT Violation). In this context, I also discuss recently suggested novel possible contributions
Brazilian Journal of Physics. Publicado em: 2005-06
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19. Efeito anomalo nas medidas de lente termica em vidros com pontos quanticos de CdTe / Anomalous effect in thermal lens measurements in CdTe quantum dot doped glasses
Semiconductor doped glasses are of great interest because of their non-linear optical properties and short response time due to quantum confinement. In this work, we used the thermal lens technique to determine the thermal diffusivity (a ) and the behavior of the temperature coefficient of the refractive index (dn/dT ) in CdTe doped borosilicate glasses trea
Publicado em: 2005
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20. Espectrometro de ressonancia de spin eletronico para amostras com baixo numero de spins
O objetivo deste trabalho é construir uma instrumentação que permita a realização de ressonância de spin eletrônico (ESR) em amostras com baixo número de spins, como, por exemplo, pontos quânticos (QDs) auto-formados de InAs. Para isto, este trabalho se propõe em usar cavidades de microfita (MRs). Apesar do seu baixo fator de qualidade, MRs apresen
Publicado em: 2005
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21. Medidas de lente termica em vidros borossilicato com pontos quanticos de CdTe / Thermal lens measurenments in quantum dots borossilicate glasses
Os vidros dopados com semicondutores são objeto de grande interesse como materiais ópticos não lineares e estudos intensivos acerca dos efeitos de confinamento quântico e não linearidade ótica tem sido realizados. Apesar do grande interesse nas propriedades óticas desses materiais, os dados térmicos e opto-térmicos são ainda escassos e raros. Neste
Publicado em: 2005
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22. AplicaÃÃo de mÃtodos correlacionados de estrutura eletrÃnica ao estudo de estados excitados de molÃculas em fase gasosa e em soluÃÃo
Ab-initio electronic structure calculations, at correlated level, are applied to the study of excited states of molecules in gas-phase and solution. The electron correlated methods comprise the multiconfigurational SCF (MCSCF), and the multi-reference CI method with single and double excitations (MR-CISD), which is used in combination with MCSCF, then provid
Publicado em: 2005
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23. Applications of quantum field theory in condensed matter
We present a brief review of some applications of quantum field theory in condensed matter systems. These include isotropic and anisotropic antiferromagnetic chains, strongly correlated organic conductors, such as the Bechgaard salts, carbon nanotubes and high-Tc superconductors. The review is by no means exhaustive and points to a vast range of new interest
Brazilian Journal of Physics. Publicado em: 2004-12
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24. Magnetotransport and Hall ferromagnetism in magnetic semiconductor heterostructures / Magneto-transporte e ferromagnetismo Hall em heteroestruturas semicondutoras magnéticas
Digital magnetic heterostructures (DMHs) are semiconductor structures with magnetic impurities (Mn) restricted to some planar arrangements (monolayers) regularly spaced. In the presence of an external magnetic field, the sp-d exchange interaction between the localized magnetic moments and the itinerant carriers is responsible for a giant spin splitting, of t
Publicado em: 2004