Um modelo consistente para o processo de fotocontagem contínua e medidas de emaranhamento de sistemas quânticos de variáveis contínuas

Detalhes bibliográficos
Ano de defesa: 2005
Autor(a) principal: Dodonov, Alexandre
Orientador(a): Mizrahi, Salomon Sylvain lattes
Banca de defesa: Não Informado pela instituição
Tipo de documento: Dissertação
Tipo de acesso: Acesso aberto
Idioma: por
Instituição de defesa: Universidade Federal de São Carlos
Programa de Pós-Graduação: Programa de Pós-Graduação em Física - PPGF
Departamento: Não Informado pela instituição
País: BR
Palavras-chave em Português:
Área do conhecimento CNPq:
Link de acesso: https://repositorio.ufscar.br/handle/20.500.14289/5070
Resumo: This dissertation embraces two trends of research in modern quantum optics. The first of them is connected to the photodetection theory, particularly to the continuous measurement theory developed by Srinivas and Davies (SD) in 1980 s, whose principal ingredient is the correct choice of the quantum jump superoperator. We deduce from first principles different possible quantum jump superoperators, and employ one of them the nonlinear quantum jump superoperator, proposed independently ad hoc by Ben-Aryeh and Brif and Oliveira et al. to study the modifications it brings to the SD theory. We call this model as E-model and generalize the both models (SD model and E-model) by including dissipation effects due to the imperfections of the cavity and of the detector. Finally, we study some specific applications of continuous photodetection theory (homodyne detection and detection of correlated photons) and compare the results between the two models. The second trend of this dissertation is related to the study of entanglement of continuous variables quantum states. We give a simplified form of Simon s separability criterion for two-mode Gaussian states, showing that for systems whose unitary evolution is governed by arbitrary time-dependent quadratic Hamiltonians, the separability dynamics is completely described in terms of the determinant of the cross-covariance matrix. As concrete examples we consider the evolution of the inverse negativity coefficient (which gives a quantitative estimation of the degree of entanglement ) for two initially uncoupled modes (each being in a squeezed thermal state) in the cases of parametric converter, parametric amplifier and for a cavity whose boundary oscillates in resonance with two field modes.