Nature's quantum secrets photosynthesis and the fifth state of matter
Bose-Einstein condensates are the "fifth state" of matter after gas, liquid, solid and plasma, and were first discovered in cold atoms at very low temperatures.
Recently, a University of Chicago team discovered a connection between photosynthesis and excitonic condensates at the atomic level - a special physical state that allows energy to flow frictionlessly through a material. The team says the discovery is scientifically intriguing and may suggest new ideas for designing electronics.
The research results were published April 28 in PRX Energy under the title "Exciton-Condensate-Like Amplification of Energy Transport in Light Harvesting.
Inside the lab, scientists at the University of Chicago marveled at the "strange" state that develops when they cool atoms to near absolute zero.
Outside their windows, trees collect sunlight and turn it into new leaves. The two may seem unrelated - but this new UChicago study shows that these processes are not as different as they seem.
The study found a connection between photosynthesis and exciton condensation at the atomic level: a strange physical state that allows energy to flow frictionlessly through a material. The authors say the finding is scientifically intriguing and may suggest new ideas for designing electronics.
Professor David Mazziotti, co-author of the study, said, "To our knowledge, these fields have never been linked before, so we find this very exciting."
Mazziotti's lab specializes in models of the complex interactions of atoms and molecules as they display interesting properties. Currently, humans have no way to see these interactions with the naked eye, so computer modeling can give scientists a window into why these behaviors occur and can also provide a basis for designing future technologies.
In particular, Mazziotti and study co-authors Anna Schouten and LeeAnn Sager-Smith have been modeling what happens at the molecular level when photosynthesis occurs.
When a photon from the sun hits a leaf, it triggers a change in a specially designed molecule - the energy shatters an electron. This electron and the "cavity" where it was once located can now "travel" around the leaf, carrying the sun's energy to another region, where it triggers a chemical reaction that produces sugar for the plant.
These moving pairs of electrons and holes are called "excitons. When the team took a bird's-eye view of how multiple excitons move, they noticed something strange: They saw patterns in the path of the excitons that looked very familiar.
-- in fact, it looked very much like the behavior in a material known as Bose-Einstein condensate. In this material, excitons can be connected into the same quantum state, like a set of bells all ringing perfectly; this allows energy to move through the material with zero friction.
According to the model created by Schouten, Sager-Smith and Mazziotti, the excitons in the leaves can sometimes be connected in a way similar to the behavior of excitonic condensates.
This was a great surprise. Exciton condensates are only seen when the material is cooled to significantly below room temperature, a bit like seeing ice cubes form in a hot cup of coffee.
Schouten explains, "Photosynthetic light harvesting takes place in a system that is at room temperature and, more importantly, has a disordered structure. This is very different from the original crystalline material and low temperatures we use to make excitonic condensates."
Although this effect is more like the formation of an "island" of condensates, Sager-Smith said, "it's still enough to enhance energy transfer in the system. In fact, their model shows that it can be as much as double the efficiency."
Mazziotti says this opens up some new possibilities for generating synthetic materials for future technologies. "A perfect ideal exciton condensate is sensitive and requires a lot of special conditions; but for realistic applications, it's exciting to see something that enhances efficiency and can happen under ambient conditions."
Mazziotti said the discovery also relates to a broader approach that his team has been exploring for a decade.
The interactions between atoms and molecules in processes such as photosynthesis are so complex that they are difficult even for supercomputers to handle, so scientists have had to simplify their models to get a handle on them. But Mazziotti believes some parts need to be preserved: "We think the local correlation of electrons (local correlation) is crucial to see how nature actually works."
Reference link:
[1] https://scitechdaily.com/natures-quantum-secret-link-discovered-between-photosynthesis-and-fifth-state-of-matter/
[2]https://phys.org/news/2023-05-scientists-link-photosynthesis-state.html
[3]https://journals.aps.org/prxenergy/abstract/10.1103/PRXEnergy.2.023002
