Signatures of three-exciton correlations in the coherent and incoherent nonlinear optical response of photosynthetic complexes

Abstract

We present a simulation study of population and coherence relaxation dynamics in the third-order nonlinear responses of the Fenna-Matthews-Olson (FMO) light-harvesting photosynthetic complex. Three-exciton correlations have been incorporated and the relevant six-point relaxation superoperator is calculated to second order in coupling to a phonon bath. The dynamics of three-exciton correlations induce new peaks that are absent or much weaker when the three-exciton variables are factorized. Such features were observed in a recent experiment (Engel G S et al 2007 Nature 446 782-6). © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.