Effect of complex inter-site couplings on the excitation energy transfer in the FMO complex

Abstract

It is believed that the quantum coherence itself cannot explain the very high excitation energy transfer (EET) efficiency in the Fenna-Matthews-Olson (FMO) complex. In this paper, we show that this is not the case if the inter-site couplings take complex values. By phenomenologically introducing phases into the inter-site couplings, we obtain a EET efficiency as high as 0.8972 in contrast to 0.6781 with real inter-site couplings. Dependence of the EET efficiency on the initial states is elaborated. Effects of fluctuations in the site energies and inter-site couplings are also examined. © 2013 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.