High Accuracy Current Comparator Technology based on Solid-state Quantum Precision Measurement

The existing high-level current ratio standard devices are all based on the principle of magnetic modulation-type comparators, with uncertainties reaching the order of 10^-6, making it difficult to further improve accuracy. This article addresses one of the main reasons limiting the improvement of accuracy in current comparators, which is the error caused by insufficient sensitivity of the Ampere balance device. Firstly, it initiates the design of a shield structure based on superconductors to reduce the impact of magnetic leakage. Secondly, it investigates a solid-state spin measurement method using diamond NV (Negatively Nitrogen Vacancy, NV) color centers. This method is based on a fixed microwave frequency and measures changes in the optically detected magnetic resonance spectrum to achieve magnetic field measurement. Through an analysis of the overall system error, theoretical limits are presented for a high-accuracy current comparator based on superconductors and solid-state quantum precision measurement.