The Collaborative Research Center (CRC/SFB) 1375 "NOA – Nonlinear Optics down to Atomic scales" was established at the Friedrich Schiller University in July 2019. The research program is focussing on exploring fundamental nonlinear processes of light-matter interaction in low-dimen­sional nanostructures, such as atomically thin layers, nanoparticles and -wires, nanostructured surfaces and molecular assemblies. NOA will explore quantum phenomena as light-induced tunneling of electrons through metallic nanogaps and field-driven carrier acceleration in plasmonic nanostructures, atomic lattices and 2D-materials. This includes investigating the resulting back-action on the electromagnetic field, causing the generation of higher harmonics and information about the electronic wavefunctions involved in the interaction.