Quantum Magnetometry

The resolution and the sensitivity of today’s magnetometers is insufficient for many future applications. In the Fraunhofer lighthouse project QMag, researchers have investigated and further developed quantum sensors for specific industrial applications. This involves two different magnetometer principles based on quantum technology concepts:

On the one hand, nitrogen-vacancy centers in diamond were used, which function as the smallest scanning magnets in an imaging scanning probe magnetometer. This turns a single atomic system into a highly sensitive sensor that can already be operated at room temperature. On the other hand, an alternative measuring method was used that exploits the magnetic field dependence of the optical properties of alkali atoms (»optically pumped alkali magnetometers«, OPM).

Both technologies work at room temperature and are suitable for industrial applications. The researchers were able to demonstrate impressive results, particularly in material testing: They have proven that the quantum magnetometers already detect changes in the magnetic field of the samples when material fatigue is not yet visible. The researchers used OPMs to measure the changes in the magnetic field of ferromagnetic material samples while they were subjected to cyclic fatigue. They have thus demonstrated that quantum magnetometers detect the smallest material defects much earlier than conventional technologies. OPMs and NV magnetometers can be used complementarily in material testing: While OPMs provide a dynamic signal from the entire sample, NV magnetometry can be used to measure the magnetic properties of individual damage on the micro- and nanoscale in detail.