The research group for quantum optics at the Institute of Applied Physics is focusing on the generation of non-classical states of light and their application using theoretical and experimental approaches. Mainly, we are studying the generation of photon pairs by spontaneous nonlinear processes in various nonlinear photonic systems ranging from bulk crystals over different waveguide structures to nanostructured or atomically thin surfaces. We aim to fundamentally understand the nonlinear effects leading to photon-pair generation and how they depend on the material and geometry of the sources. We use this understanding to tailor the properties of the generated two-photon quantum states, like spectrum, spatial distribution, and entanglement, to meet the demands of specific applications.
Furthermore, we investigate also the application of photon pairs for quantum-enhanced imaging and spectroscopy techniques, where they can enable measurements with better signal-to-noise ratio or in hardly accessible wavelength ranges. Our research on one hand tries to understand fundamental aspects of quantum measurements, including the interaction of the photons with the samples under test, to develop new imaging and spectroscopy methods. On the other hand, we aim at bringing quantum imaging and spectroscopy closer towards applications by developing integrated measurement devices.