It only takes one photon: ScienceAlert

During photosynthesis, a symphony of chemicals converts light into energy needed for plant, algae, and some bacterial life. Scientists now know that this remarkable reaction requires the least amount of light possible — just one Photon – to begin with.

A team of American researchers in quantum optics and biology has shown that a single photon can start Photosynthesis in purple bacteria Rhodobacter spiroidesand they are confident that it works in plants and algae because all photosynthetic organisms share an evolutionary ancestor and similar processes.

The team says their findings advance our knowledge of photosynthesis and will lead to a better understanding of the intersection of quantum physics in a wide range of complex biological, chemical and physical systems, including renewable fuels.

“An enormous amount of work has been done, theoretical and experimental, around the world trying to understand what happens after a photon is absorbed,” He says Graham Fleming, a biochemist at the University of California, Berkeley.

“But we realized that no one was talking about the first step. This was a question that still needed a detailed answer.”

chlorophyll Molecules receive photons from the sun, whereby an electron in chlorophyll becomes excited, and are passed on to different molecules to form the building blocks of sugar, which gives plants food and releases oxygen.

The sun doesn’t shower us with very many photons—on a sunny day, only about 1,000 photons reach a chlorophyll molecule every second—so the efficiency of photosynthesis in harnessing sunlight to produce energy-rich molecules has led scientists to believe that a single photon can start this reaction.

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“Nature has invented a very clever trick,” Fleming said He says.

The researchers focused on a well-studied structure of proteins in purple bacteria called light harvest 2 (LH2), it can absorb photons at a certain wavelength.

Using specialized tools, they created a photon source that made a pair of photons from a single photon of higher energy using Spontaneous conversion limit down.

Simplified scheme of the experimental procedure in the LH2 complex. (Janis et al nature2023)

During the pulse, the first photon, called the “herald”, was observed by a highly sensitive detector, indicating the arrival of the partner photon, which interacted with LH2 molecules in a lab sample of purple bacteria.

When a photon of wavelength 800 nanometers hit a ring of molecules in LH2, the energy went to a second ring, which gave off fluorescent photons of wavelength 850 nanometers.

In nature, this energy transfer will continue until photosynthesis begins. Finding a photon with a wavelength of 850 nanometers in the lab was a clear sign that this process had begun, especially since the structures of LH2 were separated from other parts of the cell.

The challenge was dealing with single photons, which are easy to lose. To get around this, the scientists used the beacon photon as a guide.

“I think the first thing is that this experiment showed that you can actually do things with individual photons,” He says Chemical physicist Birgitta Wally of Berkeley. “So this is a very important point.”

Using a probability distribution model and a computer algorithm, the team analyzed more than 17.7 billion photon detection events and 1.6 million fluorescent photon detection events.

The comprehensive analysis means that the researchers are confident that the results were only due to the absorption of a single photon and that no other factors could have an influence.

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a lot of Advance search Subsequent photosynthesis steps involved, after absorbing the light, sending powerful, ultrafast laser pulses to the photosynthetic molecules.

“There is a huge difference in intensity between lasers and sunlight — a typical focused laser beam is a million times brighter than sunlight,” he says. Explain Quanwei Li, a quantum physicist and engineer from Berkeley.

By showing how individual photons behave during photosynthesis, this research gives us important information about how nature’s energy conversion process works. Artificial photosynthesis technologies may one day be the key to sustainably surviving and thriving in space.

“Just as you need to understand every particle to build a quantum computer,” Lee said AddWe need to study the quantitative properties of living systems to truly understand them and create efficient synthetic systems that generate renewable fuels.

This study was a unique opportunity for two scientific fields that would not normally work together to apply and combine the techniques of quantum optics and biology.

“The next thing is, what else can we do?” He says Willie.

“Our goal is to study the energy transfer of individual photons through the photosynthesis complex on the shortest possible spatial and temporal scales.”

Research published in nature.

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