Quantum-coherent solar energy capture by marine algae

01/22/2010

16:00

S655, W&N building

Quantum-coherent solar energy capture by marine algae

Gregory D. Scholes

Faculty of Sciences

Sciences

Conference / Symposium

Speaker: Gregory D. Scholes, Department of Chemistry, Institute for Optical Sciences and Centre for Quantum Information and Quantum Control, University of Toronto


Algae are found in various habitats all over the Earth. Using photosynthesis to convert water and carbon dioxide to biomass with energy provided by sunlight, algae function as primary producers in the food chain. Cryptophytes are eukaryotic algae that live in marine and freshwater environments. They are members of an evolutionary group notable because their photosynthetic apparatus was acquired from red algae by a sequence of endosymbiotic events. As a result, cryptophyte photosynthetic antenna proteins (phycobiliproteins) exhibit exceptional spectral variation between species because they mainly use tunable linear tetrapyroles (bilins) for light-harvesting. Such antenna proteins isolated from photosynthetic organisms including algae have helped researchers learn a great deal about how excitation energy is transmitted between molecules by electronic energy transfer. Not surprisingly given the geological time scale for optimization of these systems, it has been found that plants, algae, and other photosynthetic organisms have developed tricks that lie behind their success. As an example, I will report observations of quantum coherence at ambient temperature in two evolutionarily-related light-harvesting proteins isolated from marine cryprophyte algae. Distant molecules are ‘wired’ together by quantum-coherence, which could feasibly influence light-harvesting in live cryptophyte marine algae and thus suggest biological relevance. The discovery changes the way we think about limits for how fast and how far excitation energy can be transferred. I will explain the meaning and implications of quantum-coherent energy transfer from the viewpoints of chemistry, physics and biology.