Semiclassical Regime
Mostrando 1-7 de 7 artigos, teses e dissertações.
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1. Dissipação, termalização e descoerencia via acoplamento caotico / Dissipation, thermalization and decoherence through chaotic coupling
We study here how and under which conditions a chaotic system with only two degrees of freedom can produce irreversible phenomena such as dissipation, thermalization and, from the quantum point of view, decoherence in a simple system coupled to it. In the classical formulation of the problem, we describe analytically the behavior of the energy ux in Linear R
Publicado em: 2006
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2. 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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3. Some remarks on the semi-classical limit of quantum gravity
One of the most important issues in quantum gravity is to identify its semi-classical regime. First the issue is to define for we mean by a semi-classical theory of quantum gravity, then we would like to use it to extract physical predictions. Writing an effective theory on a flat background is a way to address this problem and I explain how the non-commutat
Brazilian Journal of Physics. Publicado em: 2005-06
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4. Aplicação das funções de quase-probabilidade no estudo da dinamica de emaranhamento
Entanglement dynamics of two ideal bipartites systems is analyzed using reduced linear entropy and quasiprobability distribution functions in the semiclassical regime.Two models are studied: the quartic bidimensional oscillator and the Dicke ?s Maser model. The first one describes the propagation of two monochromatic field modes in a Kerr medium, and the sec
Publicado em: 2003
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5. Tunelamento assistido por caos em estados localizados
We have studied the effects of chaos on the tunneling of particles. As a model we used a one dimensional double well-type quartic potencial, perturbed by a periodic driving. The driving force introduces chaos and the sistem becomes mixed, exhibiting islands of regular motion immersed in a sea of chaos in its classical phase space. By altering the amplitude a
Publicado em: 2002
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6. Emaranhamento e caos em um sistema de dois spins
In this project we have studied a two spin system under an anisotropic Heisenberg interaction and external magnetic fields acting on each spin separately. We have been able to relate fast decoherence of a quantum subsystem with the presence of chaos in the corresponding classical system. Such an association has been done making use of the coherent state repr
Publicado em: 2002
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7. Estudos semiclassicos na representação de estados coerentes
In this work we develop and apply a semiclassical approximation to the coherent-state propagator K(z",z ,t) = (z"iHt/h)z ), where H is the Hamilton operator for the suystem and z) represents the coherent states of the harmonic oscilator. The semiclassical K(z",z ,t) makes use of a stationary phase approxiamtion in which stationary trajectories inhabit is stu
Publicado em: 1997