ABSTRACT
Coupled quantum dots (QDs) are of particular importance for spin-based quantum computation because universal quantum logical gates can be realized via the interaction between two quantum bits, i.e., the spins of two electrons, each trapped in one quantum dot. Analysis of the stability diagram and its evolution in magnetic fields allows one to estimate the values of the exchange energy as was demonstrated recently in the case of the two laterally coupled vertical QDs. We computed the stability diagram for model double QD systems populated with up to two electrons in magnetic fields using numerically exact diagonalization of the one- and two electrons Hamiltonian. The evolution of the stability diagrams in magnetic fields conforms to the general idea of enhanced electron localization with increasing field strength. The exchange energies extracted from the stability diagrams showed that these values are significantly overestimated when compared with numerically exact data.
