Exchange interaction and stability diagram of coupled quantum dots in magnetic fields

The charge-stability diagram for two coupled quantum dots containing up to two electrons is computed in magnetic fields. One-and two-particle Schrödinger equations are solved by exact diagonalization to obtain the chemical potentials and exchange energy in these systems. By analyzing the chemical potentials variation with external biases and magnetic fields, it is possible to distinguish between the weak and strong interdot couplings. The variation of the chemical-potential curvatures and the double-triple point separations in the stability diagrams confirms the interdot coupling decrease with increasing magnetic fields. The computed exchange energies are also found to be significantly smaller than the values estimated from the stability diagram.