Optimal and Robust Energy Transfer in Light Harvesting Complexes (Google Wkshop on Quantum Biology)

Google Workshop on Quantum Biology Optimal and Robust Energy Transfer in Light-Harvesting Complexes: A Peculiar Interplay of Quantum Coherence and Decoherence Presented by Masoud Mohseni October 22, 2010 ABSTRACT Recent advances in 2D electronic spectroscopy have provided direct evidence for existence of quantum dynamical coherence in photosynthetic energy transfer at physiological temperature. These experimental observations lead us to three main questions: How quantum coherence can persist in such warm and wet conditions? What is the role of quantum effects in their biological performance? And how we can exploit similar phenomena for designing artificial systems for efficient light-harvesting and sensing. In this talk, I address these questions and demonstrate that an interplay of quantum coherence with environmental interactions leads to optimal and robust quantum transport in these biological complexes. The performance of these systems for transporting excitation energy is explored under realistic (non-perturbative and non-Markovian) interactions to their environment. In particular, the effects of environmental strength, memory, and symmetries on the energy transfer efficiency is studied. For Fenna-Matthews-Olson (FMO) protein of green sulfur bacteria, the natural environmental parameters lay within an optimal and robust regime of energy transfer efficiency manifold. Furthermore, I will discuss whether or not the FMO complex structure is necessary for its performance and how probable is to randomly evolve into such particular geometry considering its rich parameter space. About the speaker: Dr. Mohseni is a postdoctoral fellow at the Center for Excitonics at MIT. He has been conducting research in experimental, theoretical and computational physics at the interface of quantum optics, quantum information, quantum control, physical chemistry, and biological physics. He obtained an M.Sc. in experimental quantum optics in 2003 and a Ph.D in theoretical physics in 2006 from University of Toronto. He then moved to Harvard University where he completed a two-year postdoctoral program at the Department of Chemistry and Chemical Biology. His current research addresses fundamental questions in quantum physics for understanding and controlling the interaction of light with mesoscopoic systems with potential applications to quantum transport, sensing, and imaging in biological environments. In particular, his main research interests concentrate on understanding and enhancing transport in complex quantum systems by utilizing the interplay of quantum coherence and decoherence, designing artificial systems for biosensing and light-harvesting by harnessing quantum interference effects, and quantum tomography of nanodevices and biomolecular systems via ultrafast spectroscopy.