Ac-Realisation of Resistance with Graphene (VaRG)

At RISE, all electrical units are traceable to the SI system from primary realisations of dc resistance (quantum Hall effect, QHE) and dc voltage (Josephson effect). Realisation of electrical impedance (ac resistance, capacitance, inductance) is made via long traceability chains, which gives a large measurement uncertainty and potential sources of error. 

In a previous project, a measurement system and a graphene chip were developed for the realisation of ac resistance with QHE. In this project we will make systematic precision measurements to identify possible improvements of the measurement system and develop new methods to minimise measurement uncertainty. We will manufacture and test new graphene chips with optimised design for ac resistance. We will also build new resistance standards that can maintain a lower measurement uncertainty.

This project is expected to lead to a significantly lower measurement uncertainty for ac resistance at RISE. In the long term, the measurement uncertainty for all impedance units can be improved, since the realisations of these are based on ac resistance. A primary realsation of ac resistance also has potential to open up new areas of use, such as determination of loss factors at different frequencies which is difficult without a quantum standard.