Resonance energy transfer and quantum dots

The mechanism of energy transfer between quantum dots is investigated theoretically. In order to incorporate explicit account of the selection rules for absorption of circularly polarized light, a quantum electrodynamical treatment of the electronic coupling is derived. The electronic coupling is mediated by the exchange of a virtual photon, which in the far zone limit acquires real character and is circularly polarized. A rotational average expression is also obtained. The conditions by which quantum information, in terms of exciton spin orientation (total angular momentum quantum number), can be exchanged or switched through resonance energy transfer are discussed. The spectral overlap factor is considered with explicit discussion of the roles of homogeneous and inhomogeneous line broadening. It is shown that the ensemble spectral overlap is determined by the inhomogeneous line broadening dictated by sample polydispersity.