Nonlinear quantum optics is based on the generation of quantum states of light using nonlinear processes. In this context, the Theoretical Quantum Optics group investigates possibilities to introduce novel correlations and entanglement between a different number of photons generated through special pump beams or a combination of nonlinear processes. Since one of the prime uses of entangled photons are quantum communication and quantum key distribution, this topic fits perfectly into the research direction of the Institute of Applied Physics. In the same way, such unique states foster the development of new quantum-imaging schemes based on correlation measurements.

At the same time, the group studies the generation of light through scattering processes of relativistic electrons at optical potentials and investigates the properties of the generated radiation, as well as the transition to classical free-electron lasers.