Which-way interference within ringlike unit cells for efficient energy transfer

We show that which-way interference within ringlike unit cells enhances the propagation of electronic excitations (excitons) along linear arrays made upon these basic units. After providing an analytic approximate solution of the eigenvalue problem for such aggregates, we show that the constructive interference of wave packets leads to an excitonic population transferred across the array which is not a monotonic function of the coupling between nearest-neighbor rings. The nonmonotonicity depends on an interesting trade-off between the exciton transfer speed and the amount of energy transferred, arising from the interplay between paths within the ringlike cells and the interring coupling strength across the array.