Fluctuations of interactions and the peak spacings distribution in Coulomb blockade quantum dots

Experimental and theoretical investigations of the distribution of Coulomb blockade peak spacings in chaotic quantum dots have shown a significant deviation from the Wigner–Dyson distribution predicted by the constant interaction model. Recently we introduced a random interaction matrix model for chaotic or diffusive dots that describes the crossover of the peak spacing statistics from a Wigner–Dyson distribution to a Gaussian-like distribution. Here we use this model to study the dependence of the peak-spacing distributions on the underlying space-time symmetries of the one-body Hamiltonian, and in particular we compare the cases of conserved and broken time-reversal symmetry. We also study the dependence of the peak spacing fluctuations on disorder strength in diffusive dots using a standard tight-binding Hamiltonian with Coulomb interactions. The fluctuations are found to increase with disorder and can be related to the disorder-enhanced fluctuations of the interaction matrix elements.