Optical control of the spin state of two Mn atoms in a quantum dot
  We report on the optical spectroscopy of the spin of two magnetic atoms (Mn) embedded in an individual quantum dot interacting with either a single electron, a single exciton and single trion. As a result of their interaction to a common entity, the Mn spins become correlated. The dynamics of this process is probed by time resolved spectroscopy, that permits to determine the optical orientation time in the range of a few tens of $ns$. In addition, we show that the energy of the collective spin states of the two Mn atoms can be tuned through the optical Stark effect induced by a resonant laser field. 
L. Besombes, C.L. Cao, S.Jamet, H. Boukari, J. Fernandez-Rossier
cond-mat.mes-hall