O estudo do emaranhamento na emissão espontânea no espaço livre e em uma cadeia de osciladores harmônicos acoplados

• Ano de defesa: 2010
• Autor(a) principal: Monteiro, João Frederico Haas Leandro
• Orientador(a): Silva, Fernando Luis Semião da
• Banca de defesa: Furuya, Kyoko , Pinto, Sandro Ely de Souza
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: UNIVERSIDADE ESTADUAL DE PONTA GROSSA
• Programa de Pós-Graduação: Programa de Pós-Graduação em Ciências
• Departamento: Fisica
• País: BR
• Palavras-chave em Português: emaranhamento; emissão espontânea; oscilador harmônico acoplado; sistema microeletromecânico
• Palavras-chave em Inglês: entanglement; spontaneous emission; coupled harmonic oscillator; microelectromechanical system
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA
• Link de acesso: http://tede2.uepg.br/jspui/handle/prefix/879

In this dissertation, we studied entanglement in some fundamental systems of physics, such as an excited atom in free-space spontaneously decaying and coupled harmonic oscillators. In order to study entanglement in spontaneous emission in free-space, we employed theWeisskopf-Wigner theory which allowed us to obtain the time evolution of both the atom and field states. In the case of bipartite entanglement among field modes after spontaneous emission, we showed that the modes can become highly entangled and that the features of this entanglement strongly depend on the way the partitions are made. For the entanglement between atom and field during spontaneous emission, we were able to relate entanglement to a well known physical quantity namely the lifetime of an atom in a excited state. Keeping in mind the intention to study simple but relevant physical systems, we used in the second work a chain of coupled harmonic oscillators. It was well-known among researchers in the field of quantum information that a linear chain of coupled oscillators in the rotating wave approximation and prepared in classical states would never create entanglement. Then, we used two reference oscillators prepared in squeezed states to make creation of entanglement possible. We found results concerning the relationship between the phases in the reference oscillators’ state and dynamics of entanglement in the chain for some coupling configurations. We showed that it is not always true that squeezing can favor entanglement creation and that with the configuration used by us it is possible to localize entanglement. We proposed a possible implementation of our results in coupled microelectromechanical systems.