Nonmonotonic charge occupation in double dots

TL;DR

This paper predicts nonmonotonic charge occupation in double quantum dots due to electron interactions, highlighting correlated many-body effects and proposing experimental verification methods.

Contribution

It introduces two mechanisms for nonmonotonic occupation in coupled quantum dots, linking spectral properties to many-body correlations.

Findings

Total occupation varies monotonically with gate voltage

Individual dot occupation can be nonmonotonic due to interactions

Two mechanisms identified for nonmonotonic behavior

Abstract

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 non-monotonicity is a signature of the correlated nature of the many-body wavefunction in the reduced Hilbert space of the dots. We 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.