The aim of this project is to enable an economically efficient traceability of impedance quantities to the defining constants of the revised International System of Units (SI). This will simplify the calibration support which European and other National Metrology Institutes (NMIs) provide to the electronics industries. New and easier to operate measurement bridges, convenient and easier to use graphene quantum standards, and methods to combine them will be developed. Cryogenic system components for operating the quantum devices will be developed for the challenging requirements of impedance measurements.

The overall objective is to combine novel digital impedance measurement bridges with the QHE material graphene in a simplified cryogenic environment. This will provide European NMIs, calibration centres and industry with the technology that is needed to enable the practical realisation of electrical impedance units (ohm, farad, henry) in the revised SI.

The specific objectives of the project are:

1. To optimise and to tailor graphene material and graphene devices in order to improve the understanding of the graphene AC quantised Hall effect (AC-QHE), as the basis for the traceability of impedance units to the QHE at temperatures of 4 K or higher in magnetic fields that are as low as possible - at most 6 T.
    
2. To advance digital bridges for the capacitance range from 10 pF to 10 nF at frequencies up to 100 kHz, and to develop an impedance bridge working with spectrally pure Josephson voltages up to 50 kHz in the entire complex plane.
    
3. To combine graphene devices with a Josephson impedance bridge (with a target uncertainty below 0.01 μΩ/Ω), and with a full digital bridge for simplified operation, (with a target uncertainty in the 0.1 μΩ/Ω range), in order to provide traceability for capacitance to the QHE. 
    
4. To develop and investigate a cryo-cooler system hosting the superconducting Josephson device and the graphene device, both operating at AC and serving as the core element of a quantum resistance and impedance standard in the revised SI.
    
5. To facilitate the take up of the technology and measurement infrastructure developed in the project by the measurement supply chain (e.g. graphene manufacturers), standards developing organisations and end users (e.g. NMIs and calibration centres as well as the European Commission’s Graphene Flagship).