Scientists Find Link between Photosynthesis and Quantum Physics

Saturday - May 6 2023, 17:14 UTC - 1 year ago

A study by University of Chicago scientists has found an interesting connection between atomic level behavior during photosynthesis and a quantum phenomenon called Bose-Einstein Condensate. This surprise finding could hold the key to understanding photosynthesis, and also provide insights for future electronic designs.

University of Chicago scientists hope ‘islands’ of exciton condensation may point way to new discoveries.

Scientists at the University of Chicago have found a connection between photosynthesis and exciton condensates, a state of physics that allows energy to flow without friction. This surprising finding, typically associated with materials well below room temperature, may inform future electronic design and help unravel complex atomic interactions.

Inside a lab, scientists marvel at a strange state that forms when they cool down atoms to nearly absolute zero. Outside their window, trees gather sunlight and turn them into new leaves. The two seem unrelated—but a new study from the University of Chicago suggests that these processes aren’t so different as they might appear on the surface.

The study, published in PRX Energy on April 28, found links at the atomic level between photosynthesis and exciton condensates—a strange state of physics that allows energy to flow frictionlessly through a material. The finding is scientifically intriguing and may suggest new ways to think about designing electronics, the authors said.

"As far as we know, these areas have never been connected before, so we found this very compelling and exciting," said study co-author Prof. David Mazziotti.

Mazziotti’s lab specializes in modelling the complicated interactions of atoms and molecules as they display interesting properties. There’s no way to see these interactions with the naked eye, so computer modeling can give scientists a window into why the behavior happens—and can also provide a foundation for designing future technology.

In particular, Mazziotti and study co-authors Anna Schouten and LeeAnn Sager-Smith have been modelling what happens at the molecular level when photosynthesis occurs.

When a photon from the sun strikes a leaf, it sparks a change in a specially designed molecule. The energy knocks loose an electron. The electron, and the "hole" where it once was, can now travel around the leaf, carrying the energy of the sun to another area where it triggers a chemical reaction to make sugars for the plant.

Together, that traveling electron-and-hole-pair is referred to as an "exciton." When the team took a birds-eye view and modeled how multiple excitons move around, they noticed something odd. They saw patterns in the paths of the excitons that looked remarkably familiar.

In fact, it looked very much like the behavior in a material that is known as a Bose-Einstein condensate, sometimes known as ‘the fifth state of matter.’ In this material, excitons can link up into the same quantum state—kind of like a set of bells all ringing perfectly in tune. This allows energy to move around the material with zero friction. (These sorts of strange behaviors intrigue scientists because they can be the seeds for remarkable technology—for example, a similar state called superconductivity is the basis for MRI machines).

According to the models created by Schouten, Sager-Smith and Mazziotti, the excitons in a leaf can sometimes link up in ways similar to exciton condensate behavior.

This was a huge surprise. Exciton condensates have only been seen when the material is cooled down significantly below room temperature. It’d be kind of like seeing ice cubes forming in a cup of hot coffee.

"We were astounded to see this behavior even at room temperature, where most quantum effects are washed away by thermal energy," Sager-Smith said.

Whether the team’s finding is applicable to other processes like photosynthesis remains to be seen. It could be an interesting new model for understanding photosynthesis. It could also help explain other questions, such as understanding the construction of electronic components, Mazziotti said—insight that could help inform future designs.