Tunable control and use of the spectrum of photons in quantum optics applications

One of the goals of quantum optics is to implement new sources of quantum light with tunable control of the relevant photonic properties. Here, we add to the toolkit of available techniques in quantum optics for the full control of the properties of quantum light, new strategies to manage the spectrum of photons, namely, type of frequency correlations, bandwidth and waveform. As a source of quantum light, spontaneous parametric downconversion (SPDC) is considered. Interestingly, the techniques presented might be used in any nonlinear medium and frequency band of interest. One of the schemes to control the frequency correlations makes use of light pulses with pulse-front tilt. The method is based on the proper tailoring of the group velocities of all the waves that interact in the nonlinear process, through the use of beams with angular dispersion. Noncollinear SPDC is the other strategy that is considered, since it allows mapping the spatial characteristics of the pump beam into the frequency properties of the downconverted photons.