Current-voltage asymmetries and negative differential conductance due to strong electron correlations in double quantum dots

Abstract

A theory for asymmetric current-voltage characteristics, in particular negative differential conductance, for double quantum dots with strongly correlated electron states is formulated. By expressing the double quantum dot in terms of its many-body eigenstates, a diagrammatic technique for Hubbard operator nonequilibrium Green's functions is employed. The Green's function for the double quantum dot is calculated beyond mean field theory, and it is found that the spectral weights of the conductive transitions in the double quantum dot redistribute dynamically (bias voltage dependent). The resulting asymmetric current-voltage characteristics and negative differential conductance is discussed in terms of the relative level spacing in the two quantum dots and the hopping rate between the quantum dots. Numerical results of the current-voltage characteristics are presented and compared to experiments.