New ideas continuously emerge to address fundamental and technological challenges at the intersection of materials science, nano-optics, condensed matter physics, and nanotechnology. Particularly exciting is to uncover new material systems that support robust electronic resonances that can serve as the optically active medium for next-generation nano-optoelectronic devices.  Exemplary in this regard are artificially engineered defects, so-called quantum dots, or naturally occurring defects in solids.  We are actively investigating a variety of materials – indium arsenide quantum dots, defects in transition metal dichalcogenides and defects in diamonds – as materials for solid-state quantum optics as well as for applications ranging from quantum science and nano-optoelectronics to nanoscale metrology.