Characterizing quantum-sharing of electronic excitation in molecular aggregates

A key and long standing question regarding the function of photosynthetic systems concerns the advantages that delocalized electronic excitations and their coherent dynamics could offer to robust and efficient energy transfer within and between photosynthetic light-harvesting complexes. Here we discuss how the framework of entanglement can be used to characterize the strength and spatial distribution of electronic coherences in biomolecular aggregates, why this is interesting, and how one can go about investigating possible relations between non-vanishing electronic coherences and efficient excitation transfer from donors to acceptors. As an example we discuss how certain coherences may correlate to efficient energy transfer in the Fenna-Mathews-Olson complex. Perspectives about understanding advantages of coherence-assisted energy transfer are discussed.