Photosynthesis seems almost magical. Just by exposing a plant to the sun, it produces the energy it needs to survive, grow and reproduce. It seems that a simple combination of light and chemistry shouldn’t do it. But it is clear that this is possible. We have even known for a long time how photons (or light) from the Sun fall on the chlorophyll in plant leaves and cause a chemical reaction. This reaction converts water and CO₂ it turns into glucose, which is then converted into chemical energy that nourishes the plant.

But interestingly, until recently we didn’t know exactly what it took to trigger such a reaction. We had guesses – based on how the whole process worked, we assumed that just one photon was enough to set everything in motion. We did some testing, although most of them were done with lasers, which are fundamentally different from sunlight. But we still didn’t know for sure.

“A lot of theoretical and experimental work has been done around the world to understand what happens after a photon is absorbed. But we noticed that no one mentioned the first step. One of the lead authors of the new study on the subject, Graham Fleming, said in a press release, “This still needs to be answered in detail. one question,” he said.

“No one has confirmed this assumption. [що один фотон запустить весь процес] show,” added Kuanwei Li, the study’s first author.

Flemming, Lee and the rest of the research team set out to answer this question. But to do this, they had to not only make sure that a photon was at play, but also track that single photon (which by definition literally moves at the speed of light).

The solution was to create a source of photons that would produce them in pairs: a messenger photon that would be detected during the creation of the pair, and a proton that would travel to the target. When the reporter photon was detected, the researchers observed a photon with a slightly different wavelength produced during the photosynthesis reaction.

“If you only have one photon, it’s very easy to lose it. “That was the main challenge in this experiment, and that’s why we use a reporter photon,” Fleming said in a press release.

As soon as a photon with a new wavelength was detected, the researchers realized they had proven their hypothesis – only one photon was needed to trigger the whole process (though it must be admitted that they repeated the experiment many times). According to the researchers, this experiment was particularly fascinating because of the overlap between photosynthesis and quantum mechanics.

“It was new for people working on photosynthesis because they don’t normally use these tools, and it was new for people in quantum optics because we don’t usually think of applying these techniques to complex biological systems,” said Birgitta. other lead author of the study.