A numerical study of the addition spectrum of disordered quantum dots

Numerical results pertaining to the distribution of the conductance peak sp acings of disordered interacting quantum dots are presented. The ground sta te of a dot was calculated by an exact diagonalization of a tight-binding H amiltonian for different values of interaction strength, lattice sizes, num ber of electrons and disorder. It was found that the distribution depends o n the interaction strength. For a large range of interactions which corresp ond to a regime in which the correlation between the electrons in the dot e xhibit intermediate-range order, the distribution is Gaussian with a width proportional to the charging energy. This behaviour is different from the d istribution in the weak-interaction limit which is well described by a cons tant-charging random matrix theory. Recent experiments measuring the additi on spectrum of quantum dots are performed at densities corresponding to the intermediate-range order regime and exhibit Gaussian distributions of the spacings.