Sander(-Thoemmes) leads PTB's optical-magnetometry group, building multi-channel OPM-MEG systems in world-class shielded rooms and studying auditory/sensory brain responses, magnetic nanoparticles and clinical applications. This vapour-phase approach reaches femto-to-picotesla sensitivities complementary to NV-center diamond ensemble quantum sensors (DEER, nano-NMR, T1 relaxometry) that operate near the pT/sqrt(Hz) regime.