Progress of Quantum Hall Research for Disseminating the Redefined SI

As the global implementation of new technologies continues to progress, one should hope that a more universal accessibility to the quantum SI is established. This chapter intends to give historical context for the role of the quantum Hall effect in metrology, including a basic overview of the effect, supporting metrology technologies, and how the research in this field has expanded the world’s general capabilities. The present-day era of resistance metrology, heavily dominated by the transition from using gallium-arsenide-based devices to graphene-based ones, will be summarized in terms of how the new 2D material performs, how the world has started to implement it as a resistance standard, and how the corresponding measurement infrastructure is currently adapting to the new standard. In the third section, emerging technologies based on graphene will be introduced to give a brief overview of the possible expansion device capabilities. These ideas and research avenues include p-n junction devices, quantum Hall array devices, and experimental components of ac metrology and the quantum ampere. The chapter then concludes by discussing the possible limitations of graphene-based technology for resistance metrology and looks to explore topological insulators as one potential candidate to, at the very least, supplement graphene-based QHR devices for resistance and electrical current metrology.