Superconducting instrumentation for precision measurement and control

The Josephson series-array voltage standard (JAVS) has dramatically improved the level to which high-accuracy electrical equipment may be monitored and stabilized. For example, a small pressure dependence in the output of some solid-state voltage standards had been measured with the JAVS. The use of two such series-arrays in a superconductive loop promises to be a new method of ultra-small frequency difference measurement. The accuracy of these new measurement configurations is set by the superconductive loop inductance and the Josephson junction parameters.