Contagem de fótons únicos com CCD em experimentos de óptica quântica

Abstract

In this work we discuss topics such as the theory of photon detectors, showing its operation mode, characteristics and types. In addition, we also study the quantum detection theory, how photons interact with the detector's atoms, and how the process of single and coincidences counting mode works. We look into the theory of parametric down conversion in order to create a correlated photon source and a single photon source. We also discuss about ghost imaging theory and experiments, since it shows us in a very clear way a direct appplication for a single photons camera. I present the results obtained so far with the camera we have in our laboratory. We detected the photon's cones generated by the parametric down conversion type I and type II. We recorded interference patterns, multiple slit images, and amplitude masks images with few photons. We used the CCD for photon counting in an experiment where an image of an object is obtained through photons that have not interacted with the object, but is part of one of the beams in the stimulated parametric down conversion. One of the great motivators of working with a camera is performing quantum optics experiments where spatial patterns are detected. In this aspect a camera has a greater robustness than single photon APD since it allows us to observe the whole transverse profile of a beam simultaneously, something that is possible only with a set of detectors APDs.