Figure 5

(a) Diamond plaquette. (b) Networks associated to the non-interacting TB Hamiltonian and (c) to the TB Hamiltonian with pair tunneling interacting terms of a single diamond plaquette for all different fillings of spin up particles. One localized state is shown (finite amplitudes in red) in the non-interacting network and two in the interacting network. Figure generated in Mathematica 8, https://www.wolfram.com/.