Vortex formation on Josephson junction lattices

Using relaxation techniques, the authors have simulated the flow of current vortices caused by a magnetic field applied perpendicular to a two dimensional lattice whose sites are connected by Josephson junctions. The inception of vortex flow coincides in each case with a reduction in the energy of the lattice. Different boundary conditions give rise to a different initial number of vortices, but energies per junction remain approximately the same regardless of the boundary conditions. In each case, the threshold magnetic field decreases inversely with the number of junctions in the lattice. A square ''honeycomb'' lattice, i.e. with each Josephson junction connected to nearest three instead of four neighbors, displays the similar behavior in an applied external magnetic field as an ordinary square lattice. (orig.)