Electronic devices and their components are becoming ever smaller. This creates a need for measuring instruments that are just as tiny. With a view to inspecting the smallest magnetic fields in hard discs for defects, scientists at the Fraunhofer Institute IAF are currently working on a quantum sensor that is only a few atoms in size. The tiny device is supported by an artificial diamond and is so sensitive that it can be used in many areas, including medicine where, for example, it can measure brain waves or help detect diseases early on. With the quantum sensor, the researchers are able to build an important bridge between disciplines – for the common good.