Voigt develops and benchmarks highly sensitive magnetometers (SQUID and SERF-OPM) at PTB, including standardised test benches comparing commercial OPMs to SQUID references and spin-dependent-interaction searches. 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.