The emergence of quantum technologies, using the fundamental quantum effects of superposition and entanglement, is holding solid promise for a range of breakthrough applications with high societal impact. Specific examples are the encoding of unbreakable messages using quantum cryptography or orders-of-magnitude faster quantum computers. These potentials are recognized worldwide, leading to strategic funding initiatives like the Quantum Technologies Flagship of the European Union or the German initiative QUTEGA. Also within our Abbe Center of Photonics (ACP), the development and promotion of optical Quantum Technologies have become a major field of research. ACP‘s strength lies in its demonstrated ability to fuse multiple expertises to integrate available enabling technologies into a combined research effort to open up new platforms and integrated systems exploiting Quantum Technologies. One recent example is the generation of non-classical states of light, e.g. photon pairs, by spontaneous nonlinear processes in nonlinear photonic systems ranging from bulk crystals over different waveguide structures to nanostructured or atomically thin surfaces. This understanding can be used to tailor the properties of the generated two-photon quantum states, like spectrum, spatial distribution, and entanglement, to meet the demands of specific applications. Another research focus is the development of novel quantum light sources for applications in quantum communication and sensing, efficient processing and detection schemes for high-dimensional quantum information, as well as scalable methods for the transmission of quantum states over long distances.