Terahertz fields and the dynamical control of spin in quantum dot molecules

We study the time evolution of electronic spin in a double quantum dot system (quantum dot molecule, QDM) under strong harmonic fields in the terahertz region. The dynamics of the wavefunction for a single electron includes the spin–orbit (SO) effects of both Rashba and Dresselhaus types and is obtained in terms of Floquet states and the quasienergy spectrum. A low magnetic field applied perpendicular to the plane of the QDM provides additional flexibility. We find that it is possible to control the electronic spin from a given initial state by proper choice of applied fields. The electron can be either dynamical localized or allowed to oscillate between the dots, with or without SO-induced spin flip.