A Voltage-tracking scheme for Quantum-Metrology-Triangle Experiments

To suitably perform quantum-metrology-triangle (QMT) measurements, it is required to conduct precise measurement of the difference between two voltage values-one generated from a Josephson voltage standard device, and the other derived from voltage drop in a quantum Hall resistance array device with a current applied using a single-electron pump device. During the measurement of this difference voltage, gain errors in digital voltmeters could be a source of uncertainty. Thus, in this study, we propose a method to reduce the effect of the gain errors in the digital voltmeters by minimizing the magnitude of difference voltage with real-time voltage tracking and feedback for the microwave frequency applied to the Josephson voltage standard device in the QMT measurement circuit.