In the cause of time we learned how to tailor the properties of electromagnetic fields at micro- and nanoscales using suitable photonic materials. Dielectric structures such as photonic crystals or whispering gallery resonators or metallic structures such as plates or small particles can be used for this purpose. The question is what to do with this ability?

In this seminar, I present an overview on our recent contributions that circulate around the observation and the study of quantum optical phenomena in these systems. This happens when either quantum emitters are coupled to nanophotonic systems or nonclassical light is used for the illumination. I put emphasise on basic questions that concern the methodology to make theoretical and numerical explorations but also present selected applications. Examples are quantum plasmonic metrological devices, ultrafast single photon detectors, or highly efficient sources for non-classical light.