We show that a single exciton state in an individual ordered conjugated polymer chain exhibits macroscopic quantum spatial coherence reaching tens of microns, limited by the chain length. The spatial coherence of the k=0 exciton state is demonstrated by selecting two spatially separated emitting regions of the chain and observing their interference.
@article{arxiv.cond-mat/0509095,
title = {Macroscopic coherence of a single exciton state in a polydiacetylene organic quantum wire},
author = {F. Dubin and R. Melet and T. Barisien and R. Grousson and L. Legrand and M. Schott and V. Voliotis},
journal= {arXiv preprint arXiv:cond-mat/0509095},
year = {2015}
}