A compact high-precision voltage standard based on programmable Josephson array

This paper describes a compact, portable, high-precision voltage standard based on 1 V programmable Josephson array. The accuracy of the system is estimated to be better than 4 nV. The system can realize the fully automatic measurement of voltage reference, as well as its weight and volume are reduced. "In August, 2007 this system was carried to PTB, Germany to make a comparison. The difference is about 1 nV.