Orateur
Alex Chin
(University of Cambridge)
Description
The interactions between the environment and excitons generated by light harvesting in photosynthetic pigment-protein complexes (PPC) is a key part of the remarkable, often close to 100%, quantum efficiency of solar energy transduction in natural photosynthesis. The environmental fluctuations spectra in PPCs are known to be have significant frequency structure, including strong contributions from vibrational modes with frequencies comparable to the energy differences between excitonic excited states in PPCs. In this talk, the novel non-equilibirum dynamics induced in these resonant modes by the excitation of excitons will be shown to exert a non-trivial back action on the exciton dynamics which acts to generate or regenerate electronic coherences. Importantly, it will be shown how these back actions support picosecond electronic coherences during energy transport and that these coherences may also appear spontaneously from incoherent initial conditions. This suggests that recent proposals for a quantum mechanical role in efficient, natural light harvesting may indeed be valid. This talk will introduce the basic experimental results supporting these ideas and the theoretical many-body methods which enable highly non-Markovian and correlated open quantum systems to be simulated. A more conceptual discussion of systems - as exemplified by PPCs - where the quantum sub-system and environment are not easily separated into distinct entities will also be presented.
