Optical control of the spin state in a semimagnetic quantum dot

Abstract

AbstractIn a Mn doped quantum dot the spin state of the Mn atom can be controlled via a well chosen sequence of laser pulses, which create or annihilate excitons in the quantum dot. The change of the state consists of a flip of the Mn spin accompanied by a simultaneous spin flip of an electron or light hole induced by the exchange interaction between Mn spin and electron or hole spin. All flipping processes can be interpreted in terms of exchange‐induced Rabi oscillations. The period and amplitude of the oscillations are determined by the coupling strength of the exchange interactions, which also strongly influences the energy splitting between the involved states. External magnetic fields can be used to tune the energies of the exciton states and thereby minimize the energy splitting between the states involved in the spin flip process. Thus the switching dynamics can be optimized by applying a magnetic field. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)