We show set of transformations which allow to obtain analytic solutions in several quantum-optical problems. We start with the ion-laser (time dependent) interaction, continue with the problem of a slow atom interacting with a quantized field to end with a master equation that describes losses. In all cases it is shown that one may find useful transformations that simplify the problems.
@article{arxiv.0806.4167,
title = {Useful transformations: from ion-laser interactions to master equations},
author = {R. Juárez-Amaro and J. M. Vargas-Martínez and H. Moya-Cessa},
journal= {arXiv preprint arXiv:0806.4167},
year = {2013}
}