Purple bacteria exploit quantum coherence to harvest light better

Researchers have found that purple bacteria use quantum coherence to harvest light during photosynthesis.

Inside purple bacteria chlorophyll molecules, which collect energy from light, are arranged in symmetrical rings. This geometric organisation is exceptionally good for light harvesting. 

Dr Ivan Kassal, researcher at the ARC Centre of Excellence for Engineered Quantum Systems, said that photosynthetic organisms, like the purple bacteria, have been around for billions of years.

He said, “If we can learn how they harvest light then we may be able to use these lessons to improve how we do artificial light harvesting.”

“Previous work proposed that quantum coherence, which describes the wave-like properties of particles, plays a role in light harvesting for purple bacteria.”

“We found that the geometry adopted by the purple bacteria allows for quantum coherence.”

There has been debate in the field about whether coherent effects are possible in photosynthetic systems at all.

Dr Kassal added, “This research is significant as it provides evidence of quantum effects in a biological setting.

“We know now that quantum effects cannot be neglected in studies on biological light harvesting. This is a fertile ground for developing new technologies for simulating quantum systems in noisy environments.”

Dr. Kassal hopes to apply these findings to investigations of other species, including plants.

The study also opens avenues for research into whether quantum coherence already occurs in organic solar cells, and whether we can deliberately engineer that coherence to make them more efficient.

The paper appeared in the Journal of Physical Chemistry Letters.


Media: Dr Ivan Kassal, i.kassal@uq.edu.au, +61 7 3365 7415; Tara Roberson, Communications, t.roberson@uq.edu.au, +61 7 3346 7429

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Major funding support

Australian Research Council