Numerical study of the addition spectrum of disordered quantum dots

Numerical results pertaining to the distribution of the conductance peak spacings of disordered interacting quantum dots are presented. The ground state of a dot was calculated by an exact diagonalization of a tight-binding Hamiltonian for different values of interaction strength, lattice sizes, number of electrons and disorder. It was found that the distribution depends on the interaction strength. For a large range of interactions which correspond to a regime in which the correlation between the electrons in the dot exhibit intermediate-range order, the distribution is Gaussian with a width proportional to the charging energy. This behaviour is different from the distribution in the weak-interaction limit which is well described by a constant-charging random matrix theory. Recent experiments measuring the addition spectrum of quantum dots are performed at densities corresponding to the intermediate-range order regime and exhibit Gaussian distributions of the spacings.