Single-spin optical read-out in CdTe/ZnTe quantum dot studied by photon correlation spectroscopy

Abstract

Received 9 February 2008; revised manuscript received 5 May 2008; published 5 June 2008Spin dynamics of a single electron and an exciton confined in CdTe/ZnTe quantum dot is investigated bypolarization-resolved correlation spectroscopy. Spin memory effects extending over at least a few tens ofnanoseconds have been directly observed in magnetic field and described quantitatively in terms of a simplerate equation model. We demonstrate an effective 68% all-optical read-out of the single carrier spin statethrough probing the degree of circular polarization of exciton emission after the capture of an oppositelycharged carrier. The perturbation introduced by the pulsed optical excitation serving to study the spin dynamicshas been found to be the main source of the polarization loss in the read-out process. In the limit of low laserpower, the read-out efficiency extrapolates to a value close to 100%. The measurements allowed us as well todetermine neutral exciton spin relaxation time ranging from 3.4 0.1 ns at