Os espectros de energia de átomos idealizados (isolados, parados e em temperatura 0 K) são constituídos por um conjunto de linhas muito estreitas. Contudo, no mundo real, verifica-se que cada uma destas linhas são alargadas pela ação de vários tipos de influências externas. Uma discussão simplificada é apresentada sobre seus mecanismos e como cada um deles atua isoladamente sobre as linhas espectrais. O caso de dois ou mais mecanismos atuando juntos é também considerado. Técnicas de afinamento de linha para relevantes aplicações são mencionadas, incluindo algumas que usam o controle da largura e da forma da linha laser.

The energy spectra of idealized atoms (isolated, at rest and temperature 0 K) are constituted by a set of very narrow lines. However, in the real world one verifies that each of these lines are enlarged by the action of various types of external influences. A simplified discussion is presented about their mechanisms and how each type of them acts isolated upon a thin spectral line. The case of two or more types of these mechanisms acting conjunctly is also considered. Line narrowing techniques for relevant applications are mentioned, including others using the control of the widths and the shapes of a laser line.

<p>Embora o tratamento teórico para descrever o campo luminoso na óptica quântica fosse genérico, durante bom tempo ele era referido predominantemente a modos ópticos aprisionados em cavidades. Resultados importantes foram obtidos nesse cenário. Mas, em vista da dificuldade prática no uso desse campo, trazida pelos deletérios efeitos de descoerência sobre estados aprisionados, muitos físicos da área passaram a focalizar com maior ênfase o tratamento em modos viajantes. Neste breve relato tratamos o caso da engenharia de estados não clássicos da luz para mostrar alguns detalhes das aplicações nesse cenário. Aqui a interação “campo aprisionado-átomo” dá lugar à interação “campo viajante-separador de feixes ópticos”.</p>

<p>Although the theoretical treatment to describe the light field in quantum optics was generic, during large time it was predominantly related to optical modes trapped inside cavities. Important results were then obtained in this scenario. However, in view of the practical difficulties due to the deleterious effects of decoherence upon states of trapped fields, many physicists in this area began to focus more emphasis in the treatment using traveling fields. This brief report concerns with engineering non-classical states of light field to show some details and applications in the in the later scenario. Here the interaction “atom-trapped field”, is translated into the interaction “beam splitter-traveling field”.</p>

We study two experimental schemes generating highly excited number states starting from an initial squeezed state. One of the schemes works for stationary fields, the other for traveling ones.

The occurrence of squeezing effects in coupled oscillators, and the transference between them, has been studied in various situations using Hamiltonians involving either nonlinear terms or time-dependent parameters. We consider a simplified scheme generating this effect, and discuss its origin.

Squeezed Displaced Number States of the light were introduced in the recent literature. They exhibit various nonclassical properties as sub-Poissonian statistics, squeezing and oscillations in the photon-numer distribution. Here we investigate other properties of these fields, as waiting-time and photoelectron-counting distributions. We considerably simplify previous calculations in the literature while showing that these states constitute a unified approach for number, coherent, and squeezed states.