Utilização de um formalismo quântico unificado da polarização e da coerência no estudo da informação quântica codificada na luz.

Abstract

The processing of information at the atomic level faces a problem which is decoherence. During the interactions with an environment, a composite system suffers different changes that can only be represented by its density operator. Since light has its particle behavior, it can be used to encode quantum information (in the photons), through its polarization. In this study, we analyze the interaction between a group of photons with two types of environment, describing its constituents through the Kraus operators formalism. By using the reduced density matrix method, we could represent together the behavior of coherence and polarization in a simple way by means of the unification theory between these degrees of freedom. We quantify the loss of the coherence and polarization degrees when we have environments which cause changes only in coherence of the phase during the scattering of photons and the other when these changes depend upon the polarization of the photons. In our formalism, it is possible to determine, by using the Stokes parameters, the type of polarization state. The study also shows which kind of environment should be prevented in the process of transmission of quantum information.