Anti-phase locking in a two-dimensional Josephson junction array
  We consider theoretically phase locking in a simple two-dimensional Josephson junction array consisting of two loops coupled via a joint line transverse to the bias current. Ring inductances are supposed to be small, and special emphasis is taken on the influence of external flux. Is is shown, that in the stable oscillation regime both cells oscillate with a phase shift equal to $\pi$ (i.e. anti-phase). This result may explain the low radiation output obtained so far in two-dimensional Josephson junction arrays experimentally. 
Michael Basler, Wolfram Krech, and Konstantin Yu. Platov (Friedrich   Schiller Universit\"at Jena)