Improved 10 V SINIS Series Arrays for Applications in AC Voltage Metrology

Recent metrological activities with programmable Josephson voltage standards (PJVS) are focused on extending the quantum accuracy to AC voltages, e.g. for the step-wise approximation of sine waves. Stimulated by the progress in this field, new requirements for the quality and availability of 1 V and 10 V circuits have been established. Based on the experience with programmable 1 V SINIS circuits fabricated at PTB and used at present by 13 National Metrological Institutes worldwide, the fabrication process and the microwave design were improved. The experience gained hereby enabled us to improve the properties of programmable 10 V SINIS arrays which were realized by us for the first time in 2000. The new 10 V circuits have 17 bit resolution and develop under 70 GHz microwave irradiation flat Shapiro steps at the 10 V level which are more than 600 muA wide. A direct comparison of the output voltage with a conventional 10 V SIS Josephson voltage standard confirmed the suitability for metrological applications. Incorporating 10 V-PJVS into existing AC metrology setups is expected to reduce their uncertainty budgets by about one order of magnitude.