Conductance and addition spectrum of a 2×2 quantum-dot arrayin the extended Hubbard model

We have studied the conductance and addition spectrum of a 2×2 quantum-dot array in the extended Hubbard model, i.e., when the dots are coupled to each other by both interdot tunneling and an interdot Coulomb interaction. Under parameters appropriate for experiment, both the addition spectrum and the conductance show a dramatic qualitative difference between a situation dominated by interdot Coulomb interaction and the pure Hubbard model. We calculate how, in the general case, these different contributions influence the spectra. The effects of various types of disorder are discussed.