Abstract:The application of programmable Josephson quantum voltage standard (PJVS) in electrical measurement completes the transition from physical reference standard to natural reference standard of voltage unit volt, which has the characteristics of high accuracy and high stability. Based on the double channel quantum voltage signals, the ac ratio with quantum precision can be constructed to realize the highprecision quantum reproduction of arbitrary ac voltage ratio, which can replace the traditional ac ratio technology. Through driving the SNS type double channel Josephson junction array, double quantum voltages with precise amplitude and adjustable phase can be synthesized simultaneously. The twochannel differential sampling technique is adopted to reduce the influence of step transition process on the amplitude recovery of quantum voltage, and combining the channel armchanging technique the highprecision measurement of quantum voltage ratio is realized. The standard uncertainty of the ac quantum voltage ratio measurement is 009 μV/V, and the ac quantum voltage ratio output accuracy is better than 005 μV/V. The accuracy of the ac quantum voltage ratio was verified through comparison measurement with the conventional inductive voltage divider (IVD). Finally, the applications of the ac quantum voltage ratio technology in two electromagnetic metrology fields of power measurement and ac impedance bridge are discussed.