Quantum dots based on parabolic quantum wells: importance of electronic correlations

We present measurements and theoretical interpretation of the magnetic field dependent excitation spectra of a two-electron quantum dot. The quantum dot is based on an Al${}_x$Ga${}_{1-x}$As parabolic quantum well with effective $g^{\star }$-factor close to zero. Results of tunneling spectroscopy of the four lowest states are compared to exact diagonalization calculations and a generalized Heitler–London approximation and good agreement is found. Electronic correlations, associated with the formation of an H${}_2$-type Wigner molecule, turn out to be very important in this system.