Voltage locking in two coupled microbridge Josephson junctions

Voltage locking, defined as the production of an identical non-zero DC voltage in the absence of external microwave radiation across each Josephson junction of an array, has been observed in two microbridge Josephson junctions separated by a 2μm wide strip of superconductor. Voltage locking occurs when the bridges are biased with the current flowing in opposing directions thru the bridges and out the strip connecting them. The voltage across each bridge can be pulled over 1μV until each bridge displays an identical non-zero voltage, with the total voltage across both bridges equal to zero. Full locking, as defined above, is observed in excess of 40μV. The voltage and temperature dependence of the locking is described.