Optically controlled spin dynamics in a magnetically doped quantum dot

The optically induced spin dynamics in a single quantum dot doped with a single Mn atom are studied theoretically both for the case of a magnetic field applied in Faraday configuration and in Voigt configuration. When the magnetic field is applied in Faraday configuration, the z-component of the angular momentum remains a good quantum number. We show that using a series of ultra short laser pulses manipulating both heavy and light hole excitons allows us to coherently switch the Mn spin from a given initial state into all other spin eigenstates on a picosecond time scale. By modifying the pulse sequence coherent superposition states can be prepared as well. Possible detection schemes are discussed. When the magnetic field is applied in Voigt configuration, the ultrafast optical excitation of an exciton changes the direction of the effective magnetic field acting on the Mn spin on a femtosecond time scale. This induces a precession of the Mn spin which can be efficiently controlled by the application of additional optical pulses.