10 Volt automated direct comparison of two cryocooled programmable Josephson voltage standards

We have performed direct dc comparisons between two cryocooled 10 V programmable Josephson voltage standards utilizing an automated synchronization scheme for the voltage reversals, which enables the use of a high sensitivity null detector on its 3 μV range by preventing any overload condition. No switches or manual operations are necessary to protect the null detector. Comparing the two systems under various test conditions provides robust verification of ideal system performance, and enables verification of the key components of the uncertainty budget for both the measurement methods and system operations.