Microwave emission from two-stacked arrays of long Josephson junctions

We have recorded the radiation generated by magnetic flux quanta oscillatio ns and by cavity mode oscillations in two-stacked arrays each consisting of five long Josephson junctions biased in parallel. The two arrays have in c ommon the middle electrode, which is thinner than the London penetration de pth, and can be biased independently. Basically, two kind of fluxon states can be generated, one consisting of a row of five fluxons oscillating in on e of the arrays, the other consisting of a row of Ave fluxons in one array and five antifluxons in the other array, bound in a coherent state. It is f ound from the microwave emission that the latter configuration is less sens itive to low-frequency noise.