  Photosynthetic proteins have evolved over billions of years so as to undergo
optimal energy transfer to the sites of charge separation. Based on
spectroscopically detected quantum coherences, it has been suggested that this
energy transfer is partially wavelike. This conclusion critically depends on
assignment of the coherences to the evolution of excitonic superpositions. Here
we demonstrate for a bacterial reaction centre protein that long-lived coherent
spectroscopic oscillations, which bear canonical signatures of excitonic
superpositions, are essentially vibrational excited state coherences shifted to
the ground state of the chromophores . We show that appearance of these
coherences is brought about by release of electronic energy during the energy
transfer. Our results establish how energy migrates on vibrationally hot
chromophores in the reaction centre and they call for a re-examination of
claims of quantum energy transfer in photosynthesis.
