Observation of a long-range interaction between semiconductor quantum dots

We demonstrate electromagnetic interaction between distant quantum dots (QDs), as is obsd. from transient pump-probe differential reflectivity measurements. The QD-exciton lifetime is measured as a function of the probe photon energy and shows a strong resonant behavior with respect to the QD d. of states. The obsd. exciton lifetime spectrum reveals a subradiance-like coupling between the QD, with a 12 times enhancement of the lifetime at the center of the ground state transition. This effect is due to a mutual electromagnetic coupling between resonant QDs, which extends over distances considerably beyond the nearest neighbor QD-QD sepn. [on SciFinder (R)]