Navegando por Assunto "Efeito Casimir"

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Acesso aberto (Open Access)
Criação de fótons no efeito Casimir dinâmico em cavidade oscilante com condições de Neumann e Dirichlet
(Universidade Federal do Pará, 2005-03) GRANHEN, Edney Ramos; ALVES, Danilo Teixeira; http://lattes.cnpq.br/6642002445572793
We consider a massless scalar field in a two-dimensional space-time inside an oscillating cavity with mixed boundary conditions. In order to discuss particle creation phenomenum, we consider the situation of parametric resonance in which the oscillating frequency is twice the frequency of the first mode of the static cavity. For convenience, we suppose that one of the boundaries is at rest and imposes Neumann condition to the field, whereas the other is in non-relativistic motion and imposes a Dirichlet condition on the field. Following the procedure developed by Dodonov and Klimov (Phys. Rev. A, 56, 2664 (1996)), we compute the number of created particles, the generation rate and the energy in the cavity. We compare our results with those found in the literature for the Dirichlet-Dirichlet case.
Acesso aberto (Open Access)
Efeito Casimir em teorias de Chern-Simons
(Universidade Federal do Pará, 2011) RODRIGUES, Penn Lee Menezes; PEREZ, Silvana; http://lattes.cnpq.br/3585326481456738
In this work we study the Casimir force for Maxwell-Chern-Simons (MCS) theories in (2+1) dimensions. In particular for the bidimensional case, we consider di erent boundary conditions and present new results concerning the in uence of the temperature in the phenomenon. We also analyse the Temperature Inversion Symmetry, considering both the massless and massive cases. We start by studying general aspects from Matsubara formalism with the goal of introduce thermal e ects in the theory; we also analyse general aspects of (2+1)-dimensional MCS theory. Then, we review the Casimir force for the in nite magnetically permeable lines at both zero and nite temperature, as well as the mixed lines at zero temperature, for which we take one line in nite magnetically permeable and the other perfect conducting. We next present new results concerning the Thermal Casimir force for the case of mixed lines. Finally, we analyse the Temperature Inversion Symmetry associated with the Helmholtz free energy, showing that even for the mixed lines boundary conditions it is still possible to de ne a residual symmetry, the result being analogous to previous results for the eletrodynamics in (3+1) dimensions.
Acesso aberto (Open Access)
Fenômeno de interferência na densidade de energia em cavidades com duas fronteiras oscilantes
(Universidade Federal do Pará, 2009) PIRES, Wagner Pinheiro; ALVES, Danilo Teixeira; http://lattes.cnpq.br/6642002445572793
We consider a real massless scalar field inside a cavity with two moving mirrors in a two-dimensional spacetime, satisfying Dirichlet boundary condition at the instantaneous position of the boundaries, for arbitrary and relativistic laws of motion. Considering vacuum as the initial field state, we show that the exact value of the the energy density in the cavity can be obtained by tracing back a sequence of null lines, connecting the value of the energy density at the given spacetime point to a certain known value of the energy density at a point in the region where the initial field modes are not affected by the boundaries motion. We obtain formulas for the energy density of the field and the quantum force acting on the boundaries. We also show that for a large class of movements, including resonant cases found in the literature, the exact method proposed here enable us to find analytical solutions written as series in the parameter that controls the amplitudes of the movements. Using these analytical solutions, we investigate the interference phenomena in the energy density and total energy stored in the cavity.