Optical pumping and non-destructive readout of a single magnetic   impurity spin in an InAs/GaAs quantum dot
  We report on the resonant optical pumping of the |\pm1> spin states of a single Mn dopant in an InAs/GaAs quantum dot embedded itself in a charge tuneable device. The experiment relies on a "W" scheme of transitions reached when a suitable longitudinal magnetic field is applied. The optical pumping is achieved via the resonant excitation of the central {\Lambda} system at the neutral exciton X0 energy. For a specific gate voltage, the red-shifted photoluminescence of the charged exciton X- is observed, which allows non-destructive readout of the spin polarization. An arbitrary spin preparation in the |+1> or |-1> state characterized by a polarization near or above 50% is evidenced. 
Emmanuel Baudin, Emile Benjamin, Aristide Lema\^itre and Olivier Krebs
cond-mat.mes-hall