Phase locking dynamics in 2D Josephson junction arrays with external load

Phase locking in a basic two-dimensional hybrid Josephson junction array consisting of two rows and four columns shunted by an external load is investigated, exploiting an approximation combining the ideas of harmonic balance with that of the slowly varying phase procedure. Using small ring inductances, the junction voltages within the same row oscillate nearly in-phase unless the external magnetic flux in the loops is near a multiple of a quarter of the flux quantum. Without external load we have found a stable antiphase regime where both rows carry out uniform interferometer oscillations. A stable in-phase regime, favored in an optimized radiation source, can be reached by means of an external inductive shunt for small external fields only.