Ac-Realisation of Resistance with Graphene

Purpose and goal

At RISE, all electrical units are traceable to the SI system from primary realizations of DC resistance (quantum Hall effect, QHE) and DC voltage (Josephson effect). Realization 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 this project we want to establish a primary realization of AC resistance at RISE through ac measurements of QHE in graphene.

Expected effects and result

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 realizations of these are based on AC resistance. A primary realization 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.

Planned approach and implementation

In a previous project, a measurement system and a graphene chip were developed for the realization 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 minimize measurement uncertainty. We will manufacture and test new graphene chips with optimized design for AC resistance. We will also build new resistance standards that can maintain a lower measurement uncertainty.