JOSEPHSON JUNCTION ARRAYS AND SUPERCONDUCTING WIRE NETWORKS

Techniques used to fabricate integrated circuits make it possible to construct superconducting networks containing as many as 106 wires or Josephson junctions. Such networks undergo phase transitions from resistive high-temperature states to ordered low-resistance low-temperature states. The nature of the phase transition depends strongly on controllable parameters such as the strength of the superconductivity in each wire or junction and the external magnetic field. This paper will review the physics of these phase transitions, starting with the simplest zero-magnetic field case. This leads to a Kosterlitz-Thouless transition when the junctions or wires are weak, and a simple mean-field transition when the junctions or wires are strong. Rich behavior, resulting from frustration, occurs in the presence of a magnetic field.