The effect of random positions for dipole hopping through a Rydberg gas
  We calculate the effect of two kinds of randomness on the hopping of an excitation through a nearly regular Rydberg gas. We present calculations for how fast the excitation can hop away from its starting position for different dimensional lattices and for different levels of randomness. We also examine the asymptotic in time final position of the excitation to determine whether or not the excitation can be localized. The one dimensional system is an example of Anderson localization where the randomness is in the off-diagonal elements although the long-range nature of the interaction leads to non-exponential decay with distance. The two dimensional square lattice shows a mixture of extended and localized states for large randomness while there is no visible sign of localized states for weak randomness. The three dimensional cubic lattice has few localized states even for strong randomness. 
F. Robicheaux and N. M. Gill
physics.atom-ph quant-ph