Quantum Chaos
Mostrando 1-12 de 19 artigos, teses e dissertações.
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1. Bilhares : aspectos clássicos e quânticos / Billiards : classical and quantum aspects
Fizemos um estudo sistemático dos aspectos clássicos e quânticos dos sistemas dinâmicos conhecidos como "bilhares". Introduzimos uma nova classe de bilhares classicamente caóticos cuja dinâmica quântica pode ser convenientemente descrita utilizando-se uma aproximação do tipo Galerkin, o que nos permitiu obter com boa precisão um grande numero de au
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 27/06/2012
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2. Caos quântico relativístico / Relativistic quantum chaos
Nesta dissertação analisamos bilhares usando a teoria da relatividade especial, tanto classicamente quanto quanticamente. Inicialmente revisamos a teoria de bilhares clássicos, com ênfase em como se dá sua evolução no tempo. Então estudamos a existência (ou não) de aceleração de Fermi em bilhares forçados: bilhares onde a parede se move e, quand
Publicado em: 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. Entanglement, bifurcation and chaos in the Jahn-Teller E x beta / Emaranhamento, bifurcação e caos no modelo de Jahn-Teller E x beta
In this work we realize a study of entanglement for the Jahn-Teller E Ä b model, wich describes the interaction of a qubit with an oscillator mode, and relate it with the bifurcation of the fixed point of the classical analogue of the model. We also study qualitatively the ocurrence of chaos and its variation as a function of the parameters of the system. W
Publicado em: 2009
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5. Bi-estabilidade óptica &condensação de Bose-Einstein de polaritons
Optical bistability e®ects (OB) are intrinsically related to the gain media non-linearities. In microcavities, this behavior is due to Kerr effect proportionate by polariton number, generated resonantly in strong -coupling regime, instead of the photon number. The sample was held in a cold-finger cryostat at a temperature of 10K and is constituted by two DB
Publicado em: 2008
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6. Nonlinearities in quantum mechanics
Many of the paradoxes encountered in the Copenhagen interpretation of quantum mechanics can be shown to have plausible, more logical parallels in terms of nonlinear dynamics and chaos. These include the statistical exponential decay laws, interpretations of Bell's inequalities, spontaneous symmetry breaking, and perhaps diffractive behavior and even quantiza
Brazilian Journal of Physics. Publicado em: 2005-06
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7. Quantum chaos, dynamical stability and decoherence
We discuss the stability of quantum motion under system's perturbations in the light of the corresponding classical behavior. In particular we focus our attention on the so called "fidelity" or Loschmidt echo, its relation with the decay of correlations, and discuss the quantum-classical correspondence. We then report on the numerical simulation of the doubl
Brazilian Journal of Physics. Publicado em: 2005-06
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8. Feature binding as neuron synchronization: quantum aspects
Feature binding denotes how a large collection of coupled neurons combines external signals with internal memories into new coherent patterns of meaning. An external stimulus spreads over an assembly of coupled neurons, building up a corresponding collective state. Thus, the synchronization of spike trains of many individual neurons is the basis of a coheren
Brazilian Journal of Physics. Publicado em: 2005-06
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9. Coherent states: the symplectic goup and generalizations / Estados coerentes: o grupo simplético e generalizações.
The subject of the Thesis was the aplication of the coherent states theory to non-trivial quantum systems. Starting from the general definition of coherent states for compact Lie groups, we made a detailed investigation of the construction of these states and its properties in the case of the unitary symplectic group Sp(4), which is extremely important in bo
Publicado em: 2003
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10. Estudo da dinâmica de caos no gás tridimensional de elétrons de alta mobilidade / Study of the dynamics of chaos in three-dimensional gas in electron of high mobility
A dinêmica caótica, em arranjos de bilhares eletrônicos bidimensionais e tridimensionais , em heteroestruturas semicondutoras de AlxGa1-xAs/GaAs foi estudada tanto de forma experimental como através de simulações numéricas. Como primeira parte, a dinâmica eletrônica caótica em super-redes de antipontos bidimensionais foi tratada sob a influência d
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 12/09/2002
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11. 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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12. 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