Spin control by ultra short laser pulses in a Mn doped quantum dot

Optically induced spin flip processes in quantum dots doped with a single Mn atom are discussed. On the femtosecond time scale the exciton can be controlled by ultra short laser pulses. Via the exchange interaction the Mn spin can flip on a picosecond time scale by transferring its angular momentum to the exciton. For a heavy hole system this flipping process can be described in terms of exchange‐induced Rabi oscillations between the bright and dark exciton state accompanied by a flip of the Mn spin. Because of the energy splitting between bright and dark excitons the Rabi oscillations are off‐resonant and a series of laser pulses is required to achieve a complete flip. When a light hole exciton is resonantly excited in addition to the heavy hole exciton we show that a flip of the Mn spin by two can be achieved by a series of light pulses while the exciton system returns to its initial state. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)