Exciton dynamics and Quantumness of energy transfer in the Fenna-Matthews-Olson complex

We present numerically exact results for the quantum coherent energy transfer in the Fenna-Matthews-Olson molecular aggregate under realistic physiological conditions, including vibrational fluctuations of the protein and the pigments for an experimentally determined fluctuation spectrum. We find coherence times shorter than observed experimentally. Furthermore we determine the energy transfer current and quantify its "quantumness" as the distance of the density matrix to the classical pointer states for the energy current operator. Most importantly, we find that the energy transfer happens through a "Schr\"odinger-cat" like superposition of energy current pointer states.