Single-cryostat integration of the quantum anomalous Hall and Josephson effects

By directly integrating a quantum anomalous Hall resistor (QAHR) and a programmable Josephson voltage standard (PJVS) into a single cryostat, we have implemented a unified quantum electrical instrument that provides a realization of the volt, ohm, and ampere in accordance with the revised International System of Units (SI). The quantum voltage output from this prototype ranged from (0.24 to 6.5) mV with combined relative uncertainties (k = 1) down to 3 µV/V. The colocated QAHR provided a realization of the ohm at zero magnetic field with uncertainties near 1 µΩ/Ω at R
yx
≈ 25.9 kΩ. For the ampere, a longitudinal current applied to the QAHR is converted to a quantized Hall voltage, which was directly compared to the Josephson voltage, providing measurements of the ampere that are directly traceable to the revised SI. We determined currents in the range (9.33 to 252) nA with uncertainties of (41 to 4.3) µA/A, respectively. Limitations and improvements are discussed to aid the reproduction of similar instruments at other national metrology institutes.