Artificial light harvester reveals quantum physics of efficient photosynthesis

July 14, 2015 // By Paul Buckley
A team of European research groups collaborating between universities in Vienna, Ulm, Cartagena, Prague, Berlin and Lund, have examined the quantum physics of artificial light harvesting to learn how molecular vibrations make photosynthesis such an energy efficient process.

Plants and bacteria make use of sunlight with high efficiency with as manay as nine out of ten absorbed light particles being put to use in an ordinary bacterium.

The reseachers have studied an artificial light harvester that comprises hundreds of thousands of light absorbing molecules, arranged in close proximity to one another and in an orderly fashion.

The study has shown that the quantum phenomena can be understood as a delicate interplay between vibrations and electrons of the involved molecules. The resulting theoretical model explains the experiments perfectly. The results of the study have been published in Nature Communications under the title 'Vibronic origin of long-lived coherence in an artificial molecular light harvester'.

The artificial light harvester is a supramolecule with an architecture that puts these systems in between noisy living cells and strictly organized quantum experiments at low temperatures.  Supramolecules are still governed by the same quantum effects as natural photosynthetic systems, but without the noisy background that makes their investigation so difficult in biological systems. The artificial light harvester aggregates have a diameter of less than 15 nm but has a length of micrometers

The research team employed polarized light to isolate the desired quantum-dynamical effects. Studying such ordered systems does not only further our understanding of natural photosynthesis, it also helps us to appreciate the physical mechanisms necessary for energy-efficient, cheaper, more flexible and lighter photovoltaic cells.

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