Electronic energy transfer (EET) is a ubiquitous photophysical process that plays a crucial role in the light-harvesting capabilities of natural antenna complexes, and could also hold important implications in artificial systems. Emerging experimental breakthroughs indicate that the dynamics of light harvesting is not fully described by a classical random-walk picture, but also quantum coherent transfer takes place. Interestingly, coherent EET processes are not just restricted to biological systems: similar dynamics were recently detected in a conjugated polymer at room temperature, suggesting that coherent EET may play a key role in artiﬁcial systems, as well. This suggests a new way to think about the design of future artificial photosynthetic systems and can potentially open a revolutionary avenue for the effective use of biological systems and conjugated polymers as quantum devices or resources for quantum information processing. Two far-reaching questions can be asked at this point: what is the origin of these coherent mechanisms? Can we control them? In order to tackle these questions, multichromophoric systems with helical structure are proposed as model systems.
Helical structures were not incidentally selected by nature to perform many functions in biological systems since they allow precise organization and orientation of the active chromophores. We believe that the flow of excitation energy can be coherently modulated by vibrational modes of the helix causing correlated changes in the energetic environment shared by several pigments bound to the helix. Moreover, since helixes are chiral structures, they are particularly sensitive to circularly polarized light, which can thus be exploited to characterize and control coherent mechanisms in the energy migration along the chain. This will be performed by means of novel 2D electronic spectroscopy techniques with ultrafast laser pulses and different combinations of linear and circularly polarized light.