Figure 6.

The different possible coupling regimes for an array of quantum dots. The abscissa is the dimensionless ratio 0 ≤ I/(I + β) ≤ 1, and the ordinate is the fractional disorder. For a very disordered array, the state is localized, because β is far too small, and the variations in the site energies mean that an ionic state, where some sites are doubly occupied and others are empty, is lowest in energy. Reducing the disorder allows for a greater role of the dot–dot coupling. For very low disorder, the behavior is Mott like with a transition from a delocalized to a localized phase (shown as a solid line).