On-site BIPM comparison of quantum Hall effect resistance standards and their scaling to other values

This paper reviews the implementation of an on-site comparison of quantum Hall resistance standards and their scaling to other values. This comparison, organized by the Bureau International des Poids et Mesures (BIPM), is registered as BIPM.EM-K12 and has for objective the verification of the international equivalence of the representation of the ohm between National Metrology Institutes within 1 to few parts in 10 9 . The required equipment, some technical aspects and available results are presented.