Cooperative Ordering in Lattices of Interacting Two-Level Dipoles
  We investigate the cooperative behavior of regular monolayers of driven two-level dipoles, using classical electrodynamics simulations. The dipolar response results from the interference of many cooperative eigenmodes, each frequency-shifted from the single resonant dipole case, and with a modified lifetime, due to the interactions between dipoles. Of particular interest is the kagome lattice, where the semiregular geometry permits simultaneous excitation of two dominant modes, one strongly subradiant, leading to an electromagnetically-induced-transparency-like interference in a two-level system. The interfering modes are associated with ferroelectric and antiferroelectric ordering in alternate lattice rows with long range interactions. 
Robert J. Bettles, Simon A. Gardiner, Charles S. Adams
physics.atom-ph cond-mat.quant-gas physics.optics quant-ph