Title: The role of quantum coherence and decoherence in photosynthetic complexes

Abstract: Transport phenomena are fundamental in Physics. They allow for information and energy to be exchanged between individual constituents of communication systems, networks or in biological molecules. Environmental noise is generally expected to hinder transport processes. However, and contrary to intuition, there are situations in classical systems where thermal fluctuations are actually instrumental in assisting transport phenomena. Here we show that, even at zero temperature, transport of excitations across dissipative quantum networks can be enhanced by dephasing noise. We explain the underlying physical mechanisms behind this phenomenon, show that entanglement does not play a supportive role and propose possible experimental demonstrations in quantum optics. We argue that Nature may be routinely exploiting this effect and show that the transport of excitations in light harvesting molecules does benefit from such noise assisted processes. These results point towards the possibility for designing optimized structures for transport, for example in artificial nano-structures, assisted by noise.