Graphene's Role in Advancing Quantum Electrical Standards.

National Metrology Institutes are advancing quantum electrical standards by transitioning from traditional Gallium Arsenide heterostructures to graphene-based quantum Hall devices. This major shift continues to leverage the 2018 revision of the International System of Units (SI), which sets a connection between fundamental constants of nature and calibration of weights and measures. Graphene offers more relaxed operating parameters due to its unique electronic properties, and this ultimately translates to reduced equipment costs and complexity. These improvements can make quantum electrical standards more accessible for broader adoption beyond primary metrology laboratories. Significant progress in epitaxial graphene growth and device fabrication has led to the development of quantum Hall array resistance standards, which essentially interconnect multiple graphene Hall elements, providing a wider range of quantized resistance values and shortening the calibration chain for various applications. Recent advancements indicate that the use of star-mesh configurations achieve even higher quantized resistance values, promising a more flexible and universal quantum electrical reference.