Exploiting quantum coherent energy transfer in light-harvesting systems

It is believed that with a broad understanding of how natural photosynthetic systems work, we might be able to create artificial systems that would use solar light as efficient, sustainable and carbon-neutral source of energy. Important experimental breakthroughs have recently shown that quantum coherent transfer of photo-excitation takes place in natural light-harvesting systems. This suggests a new way to think about the design of future artificial photosynthetic systems and a far-reaching question can be asked at this point: how can quantum coherence and quantum correlations be exploited in the design of new energy transfer devices? In order to tackle this question the proposed research aims at linking the conceptual framework of Quantum information Science with the characterisation of excitation transfer in molecular complexes. Apart from biomolecular complexes, of particular interest is also the excitation transfer dynamics in other supramolecular systems such as DNA-based molecular photonic wires. A central characteristic common to all these scenarios is that the systems of interests, i.e. coupled pigments, are embedded in rather complex and fluctuating environments, i.e. protein. Remarkably, recent experimental studies show that preservation of coherence in some of these molecular aggregates relies on the fact that close units share the same protein environment as opposed to the common belief that environmental modes act locally. These unique features open up different possibilities to control and manipulate photo-excitation transfer dynamics. This research will therefore focus on addressing three important aspects that represent challenges in the manipulation of such systems as functional devices: (i) the role of quantum coherence and quantum correlations in the efficiency of energy transfer, (ii) the effects of correlated environments, and (iii) the robustness of such coherence to static and dynamic fluctuations. Collaborations with experimental groups will ensure that unambiguous ways to identify and exploit quantum coherence and correlations in such molecular complexes are proposed. The results can have potentially high-impact on the design of new technologies exploiting solar light efficiently. From a more fundamental viewpoint, this research will help to gain important insights into the function of quantum coherence during the primary events in photosynthesis.