High-efficiency frequency generation in a periodic array of Josephson junctions

Electrodynamic behavior of a periodic array of Josephson junctions is considered in a squeezed geometry. The ``squeezing'' is represented by external superconducting screens which substantially enhance nonlocal interactions between individual junctions. These interactions are vital for synchronization in the whole system. In order to find the value of a synchronization parameter (difference in phase between adjacent junctions) the principle of maximum entropy production is applied. This principle leads to appearance of bands inherent to the one-dimensional periodicity of the system. It is shown that in the absence of dissipation in the transmission line (which also, in the given geometry, serves to enhance interactions between junctions), there is a single mode of oscillations with extreme efficiency. This mode allows for oscillations in a very wide range of frequencies. The mode exhibits resemblance, in its internal features, to the appearance of a broken symmetry phase in second-order phase transitions. {} 1996 The American Physical Society.