van Loock leads theoretical quantum optics and quantum information at Mainz, with a long-standing focus on continuous-variable quantum optics: squeezed and other nonclassical Gaussian states, non-Gaussian resources such as cat and GKP states, hybrid discrete/continuous-variable encodings, and the error-correction and repeater architectures built on them. The group also works on the fundamental limits of quantum-enhanced measurement and on how nonclassical light can be used as a metrological resource. He is theory-first, with output that directly serves the experimental quantum-optics and trapped-ion groups in Mainz. Relative to the established NV-ensemble quantum-sensing playbook (DEER, nanoscale NMR, T1 relaxometry at pT/sqrt(Hz) ensemble sensitivity), the relevance is on the fundamental-light-physics axis rather than the magnetometry axis: this is where the squeezing/nonclassical-state theory sits that would let a spin-ensemble sensor beat the standard quantum limit.