Mesoscopic Systems
Mostrando 1-12 de 17 artigos, teses e dissertações.
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1. O campo eletromagnético quantizado submetido a ruído e acoplado a um oscilador mecânico / The quantized electromagnetic field submitted to noise and coupled to a mechanical oscillator
In this project we will investigate the influence of noise in the process of interaction of radiation (quantized field) with the matter (mesoscopic mechanical system). We will consider the mode field confined in a cavity of high quality factor with a fixed mirror and one moving mirror, this treated as a mechanical oscillator susceptible to radiation pressure
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 14/05/2012
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2. Dinâmica quântica de um circuito RLC mesoscópico
Nesta dissertação, apresentamos uma descrição quântica de um circuito RLC mesoscópico sem fonte. Com esta finalidade, modelamos este sistema para aquele de um oscilador harmônico amortecido, que é descrito pelo Hamiltoniano de Caldirola-Kanai. Então, com a ajuda do método de invariantes quânticos, resolvemos a equação de Schrödinger para este H
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 30/06/2011
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3. Nonadditive entropy and nonextensive statistical mechanics -an overview after 20 years
Statistical mechanics constitutes one of the pillars of contemporary physics. Recognized as such - together with mechanics (classical, quantum, relativistic), electromagnetism and thermodynamics -, it is one of the mandatory theories studied at virtually all the intermediate-and advanced-level courses of physics around the world. As it normally happens with
Brazilian Journal of Physics. Publicado em: 2009-08
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4. Ruido no transporte eletronico em sistemas mesoscopicos / Noise in the electronic transport in mesoscopic systems
This dissertation describes the fundamental caracteristics of mesoscopic conductors, and the origins and properties of the sources of noise in conductors. Firstly, we describe the noise through different methods and emphasize the properties of each kind of noise. In the following, we present the scattering approach for coherent phase conductors, which allows
Publicado em: 2009
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5. Localization of electronic states in DNA-like double strand model / Localização eletronica em cadeias duplas : aplicação ao DNA
In this work we discuss and compare different definitions for localization of electronic states in quase-one-dimensional systems: the 1-D case of polianilines chains and DNA-like molecules. In order to establish ranges of equivalence, the localization length from both, the conductance and participation ratio, is computed. For the 1-D case the con-ductance is
Publicado em: 2008
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6. AnÃlise e resultados experimentais de sistemas de distribuiÃÃo quÃntica de chaves usando fÃtons isolados e estados coerentes mesoscÃpicos. / Theorical analysis and experimental results of quantum key distribution systems using single-photons and mesoscopic coherent states
In this dissertation it is realized a study about quantum key distribution (QKD) in optical networks. Initially, a review of the theory of quantum key distribution and some of its implementations with strongly attenuated coherent states, as well a review of an optical system for physical encryptation using mesoscopic coherent states are realized. Following,
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 13/09/2006
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7. Transporte em nanoestruturas: mÃtodos de movimento Browniano e teoria de circuitos
The results presented in this thesis can be divided into two parts. In the first one we study a class of Brownian motion ensembles (BME) obtained from the general theory of matricial Markovian stochastic processes of random matrix theory. The ensembles are characterized by a Fokker-Planck equation and are closely related to Hamiltonians of Calogero-Sutherlan
Publicado em: 2006
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8. AnÃlise e resultados experimentais de sistemas de distribuiÃÃo quÃntica de chaves usando fÃtons isolados e estados coerentes mesoscÃpicos / Theoretical analysis and experimental results of quantum key distribution systems using single-photons and mesoscopic coherent states.
Nesta dissertaÃÃo à realizado um estudo sobre implementaÃÃes de distribuiÃÃo quÃntica de chaves (DQC) em redes Ãpticas. Inicialmente, à feita uma revisÃo da teoria da distribuiÃÃo quÃntica de chaves com fÃtons isolados e de algumas implementaÃÃes com estados coerentes fortemente atenuados, bem como a revisÃo de um sistema Ãptico para encri
Publicado em: 2006
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9. Espectroscopia de tunelamento em sistemas nanoscopicos de transporte balistico
In this work we discuss the ballistic transport properties of non-interacting electrons in confined nanoscopic system, where the sample boundaries and a controllable impurity repulsive, such as the one induced by scanning a Atomic Force Microscope tip or using split gates technique are the only source of electron sacttering. Two quantum scenary are studied:
Publicado em: 2003
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10. Effect of the lead dimensionality over transport properties in quantum dots
We theoretically investigate the effect of the lead dimensionality on the non-equilibrium electron transport through quantum dots. More precisely, we study nonlinear transport in a quantum dot coupled to leads of diverse dimensionality. We show that the presence of the latter strongly determines the resulting transport properties. Differently from higher dim
Brazilian Journal of Physics. Publicado em: 2002-06
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11. Estudo de Fases Termotrópicas por Microscopia Óptica, Medidas de Densidade, Entálpicas e Espalhamento de Raios X / Thermotropic phase study, by optical microscopy, density and calorimetric measurements and X-ray scattering.
The influence of the mean molecular length on the nature of the smectic A (SA)- cholesteric (C) liquid crystal phase transition has been studied for cholesteryl myristate (C14), cholesteryl nonanoate (C9) and binary mixtures of C14 and C9 and cholesteryl caproate (C6) and C9. Optical microscopy was carried out to determine the temperatures of the SAC as weel
Publicado em: 2000
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12. Bilhares quanticos como modelo para um gas mesoscopico magnetizado
During the last years, mesoscopic systems have been attracting much interest in Theoretical Physics, due to the implementation of important theories in this field such as the semiclassical theory of periodic, classical, orbits. The recent progresses in experimental techniques, in semiconductor materials, showed that the manipulation of real systems with as f
Publicado em: 1998