Quantum technologies challenge metrology like no other field as they require a signal/noise ratio and resolution in space and time at the sensitivity limit – if not beyond – of many characterization techniques. 

Today, the highly brilliant X‐ray beams generated at electron‐storage rings play a key role in research from materials science to the study of physical quantum phenomena. Through general user proposal schemes, access to the specialized instruments is offered to the scientific community, and dedicated beamlines enable insights into quantum materials and devices made thereof. We will give an overview of X‐ray characterization with a focus on scanning Xray nanoscopy that offers an entire suite of techniques, from the quantification of the elemental distribution and chemical speciation to the measurement of the nanoscale strain around defects or the evaluation of the local electrical and optical performance.

The field of X‐ray nanoscopy has particularly profited from two recent developments: first, novel X‐ray focusing optics enable highly coherent, intense X‐ray beams at the nanoscale. Second, diffraction‐limited storage rings boost the brilliance by orders of magnitude. The first diffraction‐limited storage rings have ramped up user operation, and more will follow in the coming years.

Based on our background in photovoltaics and semiconductor metrology, we will present exemplary measurements at state‐of‐the‐art nanoprobe endstations at DESY (Germany), ESRF (France), MAX IV (Sweden) as well as APS and NSLS II (both USA). Beyond the actual applications, we will highlight possibilities and challenges related to X‐ray nanoscopy and sketch ‘dream experiments’ in the field of quantum technology in general and implanted single impurities in particular to spark discussions.