Quantum effect in plant photosynthesis mystery
Scientists have observed what happens at the subatomic level during the very first stage of photosynthesis and uncovered a much deeper interaction than had previously been considered possible. The researchers (U.S. Department of Energy’s Argonne National Laboratory and the University of Notre Dame), have published their research findings in the “Proceedings of the National Academy of Sciences”. This new work builds on from an earlier Berkeley university study that examines how quantum entanglement emerges as the quantum coherence in photosynthetic systems evolves.
Biochemist David Tiede explains that while the different species of plants, algae and bacteria have evolved over time a variety of different mechanisms to effectively harvest light energy, they all share a feature known as a photosynthetic reaction centre. Pigments and proteins found in the reaction centre help organisms perform the initial stage of energy conversion. These pigment molecules, known as chromophores, are responsible for absorbing the energy carried by incoming light. After a photon hits the cell, it excites one of the electrons inside the chromophores.
As Researches observed the initial step of the process, the scientists saw something no one had ever observed before, that is that a single photon appeared to excite different chromophores simultaneously. “The behaviour we were able to see at these very fast time scales implies a much more sophisticated mixing of electronic states,” Researches commented. “It shows us that high-level biological systems could indeed be tapped into very fundamental physics in a way that didn’t seem likely or even possible.”
The quantum effects observed in the experiment may suggest that the natural light-harvesting processes involved in photosynthesis may be much more efficient than previously indicated by previous classic biophysics studies. It leaves us wondering how did Nature create this incredibly elegant solution.
The results of this latest study will eventually influence the creation of artificial materials and devices that can imitate natural photosynthetic systems. “The level that we are at with artificial photosynthesis is that we can make the pigments and stick them together, but we cannot duplicate any of the external environments,” explained researchers. “The next step is to build in this framework, and then these kinds of quantum effects may become more apparent.”
The moment when the quantum effect occurs is so short-lived (less than a trillionth of a second); scientists will have a hard time ascertaining biological and physical rationales for the effect’s existence in the first place. It makes us wonder if they are really just there by accident or if they are telling us something subtle and unique about these materials. Whatever the case, we’re getting at the fundamentals of the first step of energy conversion in photosynthesis.