Klaus v. Klitzing, Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany
The quantum Hall effect is in the focus of interest not only because of new research fields like quantum computation or topological insulator but also for his contribution in metrology (science of measurements). The comparisons of the quantized Hall resistance for different materials (silicon, gallium arsenide or graphene) demonstrate the universality of this resistance within the experimental uncertainty of about one part in 1010 and it is generally accepted, that at this level of accuracy the experimental result is identical with the fundamental constant h/e2. This conclusion is important for the present discussion of introducing fundamental constants as new base units for our international system of units. The talk summarizes the contribution of the QHE in this field and the status of a new realization of the base unit of mass, the kilogram.