ABSTRACT
As natural extensions of the concept of artificial atoms, coupled quantum dots (QD) resemble natural molecules and offer enhanced many-body tunability by electrically varying the coupling barrier or distance between the dots, which are fundamental technical ingredients for realizing a quantum logic gate. The symmetry of the electron wave functions is of crucial importance for the evolution of the energy spectrum of molecular systems under the influence of perturbations. According to the von Neumann–Wigner theorem, energy levels cross for states that bear different symmetries, while they anticross for states with the same symmetry. For small nonzero magnetic field, the triplet energy level crossing in coupled dots with large aspect ratios evolves into anticrossing due to the mixing of single-particle states bearing different spatial symmetry. For even larger magnetic fields, the localization of electrons by detuning is more abrupt due to the strong compression of electronic orbitals.
