Electrically controllable g tensors in quantum dot molecules

We present a quantitative theoretical analysis of electron, hole, and exciton g tensors of vertically coupled InAs/GaAs quantum dot pairs in external electric and magnetic fields. For magnetic fields lying in the growth plane, we predict a giant electrically tunable anisotropy of hole g factors that is introduced by piezoelectric charges. This effect allows bias controlled g factor switching and single-spin manipulations in a static magnetic field. We use a relativistic eight-band k center dot p envelope function method including strain, which accounts for magnetic fields in a gauge-invariant manner. In a regime where the molecular wave functions form bonding and antibonding orbitals and for vertical magnetic fields, our results reproduce experimentally observed resonant enhancements of exciton g factors without any fitting parameters.