Nonmonotonic charge occupation in double dots -: art. no. 201308

We study the occupation of two electrostatically coupled single-level quantum dots with spinless electrons as a function of gate voltage. While the total occupation of the double-dot system varies monotonically with gate voltage, we predict that the competition between tunneling and Coulomb interaction can give rise to a nonmonotonic filling of the individual quantum dots. This nonmonotonicity is a signature of the correlated nature of the many-body wave function in the reduced Hilbert space of the dots. W identify two mechanisms for this nonmonotonic behavior, which are associated with changes in the spectral weights and the positions, respectively, of the excitation spectra of the individual quantum dots. An experimental setup to test these predictions is proposed.