Asymmetric optical nuclear spin pumping in a single uncharged quantum dot

作者：Klotz F^*; Jovanov V; Kierig J; Clark E C; Bichler M; Abstreiter G; Brandt M S; Finley J J; Schwager H; Giedke G

来源：Physical Review B, 2010, 82(12): 121307.

DOI：10.1103/PhysRevB.82.121307

Highly asymmetric dynamic nuclear spin pumping is observed in a single self-assembled InGaAs quantum dot subject to resonant optical excitation of the neutral exciton transition. A large maximum polarization of 54% is observed and the effect is found to be much stronger upon pumping of the higher energy Zeeman level. Time-resolved measurements allow us to directly monitor the buildup of the nuclear spin polarization in real time and to quantitatively study the dynamics of the process. A strong dependence of the observed dynamic nuclear polarization on the applied magnetic field is found, with resonances in the pumping efficiency observed for particular magnetic fields. We develop a model that accounts for the observed behavior, where the pumping of the nuclear spin system is due to hyperfine-mediated spin-flip transitions between the states of the neutral exciton manifold.

• 出版日期2010-9-21