CIPM MRA COMPARISON REPORTS

A comparison of the DC primary voltage realisation and a comparison of the root mean square (RMS) amplitude of a sinewave (AC signal) were performed between the Bureau International des Poids et Mesures (BIPM) and the Centro Nacional de Metrología (CENAM) in the CENAM laboratory in Querétaro, Mexico in August 2025. For the DC comparison, the BIPM transportable Programmable Josephson Voltage Standard (BIPM-PJVS) was directly compared to the CENAM Programmable Josephson Voltage Standard (CENAM-PJVS) by means of an analog nanovoltmeter at 1 V and 10 V. For the AC comparison, the AC signal generated by a BIPM generator was measured alternatively by the BIPM-PJVS and the CENAM-PJVS. The comparison was carried out at RMS voltages of 0.75 V and 7 V at different frequencies in the range from 62.5 Hz to 1250 Hz. This is the second key comparison since the extension of the BIPM.EM-K10 comparison protocol to AC measurements, endorsed by the Consultative Committee for Electricity and Magnetism (CCEM) in June 2022. The relative agreement between the two quantum voltage standards was within 3.6 parts in 10¹¹ and 5.7 parts in 10¹⁰ at 10 V DC and 1 V DC, respectively. The final results of the AC measurements were also in good agreement, to within a few parts in 10⁷ at 0.75 V RMS for several frequencies and a few parts in 10⁹ at 7 V RMS at 62.5 Hz, respectively.