Exchange-controlled spin dynamics in coupled quantum dots

We measure circular polarization memory of neutral exciton states with polarization dependent photoluminescence spectra. As a consequence of anisotropic exchange interaction a low degree of circular polarization memory was observed in the spatially direct and indirect excitons where they anticross. With applied electric field as we tune the excitonic emission from intra-dot to inter-dot the electron-hole wave function overlap reduces and we observe an increase in polarization memory due to reduced exchange interaction. We observe a sudden unexpected dip in circular polarization memory of the spatially indirect exciton state that is coincident with the applied field where the single hole level resonance is observed. Possible mechanisms for this loss of circular polarization memory will be presented.