  We investigate the role of quantum coherence in modulating the energy
transfer rate between two independent energy donors and a single acceptor
participating in an excitonic energy transfer process. The energy transfer rate
depends explicitly on the nature of the initial coherent superposition state of
the two donors and we connect it to the observed absorption profile of the
acceptor and the stimulated emission profile of the energy donors. We consider
simple models with mesoscopic environments interacting with the donors and the
acceptor and compare the expression we obtained for the energy transfer rate
with the results of numerical integration.
