Excitation spectra of two correlated electrons in a quantum dot

Abstract

Measurements and a theoretical interpretation of the excitation spectrum of a two‐electron quantum dot fabricated on a parabolic Ga[Al]As quantum well are reported. Experimentally, excited states are found beyond the well‐known lowest singlet‐ and triplet states. These states can be reproduced in an exact diagonalization calculation of a parabolic dot with moderate in‐plane anisotropy. The calculated spectra are in reasonable quantitative agreement with the measurement, and suggest that correlations between the electrons play a significant role in this system. Comparison of the exact results with the restricted Hartree—Fock and the generalized Heitler—London approach shows that the latter is more appropriate for this system because it can account for the spatial correlation of the electron states.