Collective synchronization of arrays of superconducting thin-film microbridges

Square networks (arrays) of superconducting thin-film ''Dayem'' microbridges have been investigated. Due to the uniform properties of our bridges, it was particularly easy to collectively synchronize these networks to a microwave field. Analogue computer calculations indicate that to obtain a free-running single-frequency 2 x 2 network, the diagonal pairs of junctions must be matched approximately to each other and be different from the other pair. We expect this to be a necessary condition for frequency and phase locking in larger networks, but as yet we have not realized this situation experimentally