Par de Lax, reservatório unidimensional no contexto de sistemas quânticos abertos

Abstract

Since the establishment of quantum mechanics, in order to verify and

explore quantum systems such as atoms and molecules, it has been sought stra- tegies to isolate these systems. Although the complete isolation is practically

unattainable, it has recently emerged the interest and ability to control this envi- ronment, which may show novelty in the dynamics of the system. We study the

dynamics of a quantum system coupled to the quantum electromagnetic field in a one-dimensional waveguide (1D). In this context, the quantized electromagnetic field acts as a reservoir. First, we present the central concepts involving the theory of open quantum systems. We present a review of spontaneous emission concepts, studying the behavior of the dynamic of the excited state population of a two level atom, both in the free space as in an optical cavity, composed by a pair of mirrors. In quantum optics, optical cavity induces oscillations in the dynamics of the excited state population of the atom. This oscillation is caused by the reflection of the excitation into the eletromagnetic field, the photon, by the mirrors. In this thesis, we study the dynamics of a two-level atom in an one-dimensional infinity waveguide where the field is prepared with a single photon package and we show that the dynamics of the excited state population may show an oscillatory behavior. In this case, the physical source of the oscillations is a novelty. We reveal that the origin of it is due the interference between the probability amplitude of the excitation be in the input field and the probability amplitude of it be in the atom. We analyzed the dependence of the oscillation with two experimentally controllable parameters, the length of the package and its central frequency. We also show an application of this study of the concept of Non-Markovian dynamics, where we find that the oscillatory

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iv behavior in the dynamics of the excited state of the atom is a signature of Non-Markovianity. We finish this thesis explaining ways to observe this behavior experimentally exclusively by measuring the input and output fields of the guide.