JOSEPHSON-JUNCTION NETWORKS AND ROUGHENING PROBLEMS

We discuss the phase diagram of regular networks of quantum mechanical Josephson junctions in one and two dimensions for different choices of the Coulomb interaction between pairs. In a particular case this is equivalent to a quantum interface with lateral tunneling along the boundary. Using a functional integral approach the partition function is transformed into that of classical roughening or Coulomb gas problems. It is shown, in particular, that the structure of the phase diagram depends crucially on the form of the Coulomb interaction and that with dissipative interactions both globally and locally superconducting phases are possible. The relation of our results to recent experiments on granular superconducting films and ideal Josephson junction arrays is discussed briefly. © 1990 Springer-Verlag.