Semiclassical Limit
Mostrando 1-12 de 12 artigos, teses e dissertações.
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1. Microlasers de cavidades estadio aplicados a detecção nanovolumetrica / Stadium cavities microlasers applied to the nanovolumetric detection
This work presents the development of resonant cavities based on chaotic billiard geometries built with semiconductor active optical medium for sensing applications. In spite of the classically chaotic behavior of the stadium, the quantum description of the problem in the semi-classical limit shows unexpected accumulations of the density of probability on cl
Publicado em: 2010
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2. Instantonic methods for quantum tunneling in finite size
The instantonic approach for a Φ4 model potential is reexamined in the asymptotic limit. The path integral of the system is derived in semiclassical approximation expanding the action around the classical background. It is shown that the singularity in the path integral, arising from the zero mode in the quantum fluctuation spectrum, can be tackled only ass
Brazilian Journal of Physics. Publicado em: 2009-12
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3. Integrals in the coherent state representation / Integrais de trajetoria na representação de estados coerentes
The overcompleteness of the coherent states basis gives rise to a multiplicity of representations of Feynman?s path integral. These different representations, although equivalent quantum mechanically, lead to different semiclassical limits. Baranger et al derived the semiclassical limit of two path integral forms suggested by Klauder and Skagerstam. Each of
Publicado em: 2008
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4. Production of 1s2s2p4P states by transfer-loss cascades in O5+ collisions with he and H2 targets
Single differential cross-sections for transfer-loss (TL) leading to the production of O5+(1s2s³S)nl4L states were computed for 0.2-1.2 MeV/u collisions of O5+(1s²2s) ions with He and H2 targets. At these collision energies, 1s loss is significant and electron transfer to n = 3-4 levels is dominant. Furthermore, due to spin conservation, quartet states can
Brazilian Journal of Physics. Publicado em: 2006-06
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5. Validity of semiclassical gravity in the stochastic gravity approach
In semiclassical gravity the back-reaction of the classical gravitational field interacting with quantum matter fields is described by the semiclassical Einstein equations. A criterion for the validity of semiclassical gravity based on the stability of the solutions of the semiclassical Einstein equations with respect to quantum metric perturbations is discu
Brazilian Journal of Physics. Publicado em: 2005-06
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6. 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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7. A new form of path integral for the coherent states representation and its semiclassical limit
The overcompleteness of the coherent states basis leads to a multiplicity of representations of Feynman's path integral. These different representations, although equivalent quantum mechanically, lead to different semiclassical limits. Two such semiclassical formulas were derived in [1] for the two corresponding path integral forms suggested by Klauder and S
Brazilian Journal of Physics. Publicado em: 2005-03
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8. Semiclassical propagation of coherent states / Propagação semiclassica de estados coerentes
This thesis addresses di®erent aspects of the semiclassical propagation of coherent states. We have derived a general expression for the propagator connecting these states which, di®erently from previous formulae in the literature, is valid for packets of arbitrary widths. The result, obtained via functional integration, depends on classical trajectories i
Publicado em: 2005
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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. 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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11. Teoria da seção de Bogomolny para o estadio
The quarter-stadium can be decomposed into a rectangle and a quarter-circle; in each of these regions the Helmholtz equation is separable. We thus explicitly construct Green functions for both regions and a fully quantum mechanical Bogomolny finite matrix including real and evanescent waves is built. The eigenvalues and the eigenfunctions calculated with ext
Publicado em: 1997
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12. Reduction, the trace formula, and semiclassical asymptotics
We state a theorem that relates the theory of dimensional reduction in Hamiltonian mechanics to the spectral properties of elliptic operators with symmetries on compact manifolds. As an application, we show that the spectrum of the Schrödinger operator, -[unk]hΔ + V, as [unk]h → 0, contains geometric information about the closed trajectories of a classic