A programmable Josephson voltage standard (PJVS) was set up at the Standards and Calibration Laboratory (SCL) in March 2018. The PJVS is an intrinsic standard for direct current (DC) voltage which was developed by the National Institute of Standards and Technology (NIST) of the United States. It operates on a quantum physics superconducting principle, the Josephson effect. It is currently used for the practical realisation of the DC voltage with the smallest measurement uncertainty. The new system ensures the voltage standard maintained by the SCL is in line with the world’s most advanced national metrology institutes (NMIs).

Dr Samuel Benz, a world renowned pioneer in Josephson voltage standard and the Fellow and Group Leader of the NIST Superconductive Electronics Group, visited the SCL during the system installation and had a technical exchange with the staff of SCL. Dr. Benz introduced that the system could generate quantum-accurate DC voltage over the range from -10 volts to +10 volts with an accuracy of 1 part in 10⁹.

The new programmable feature enables the generation of stable DC voltages and stepwise alternating current (AC) waveforms, which could be further developed as the measurement standard for low frequency AC voltage. After the system setup, the performance of the system was validated by direct comparison with a NIST transportable PJVS system at the smallest uncertainty level.