The conversion of light into useful energy in green plants is carried out in two stages: first sunlight is collected by "antenna chlorophyll" optimized for absorption; Next the light energy is transferred to a "reaction chlorophyll complex" where it is transformed into a chemical form useful for running the plant's machinery. Recently an international group of scientists have discovered that, in at least one species of ocean algae, the process of energy transfer between antenna and reaction sites is so efficient that it can only explained by a quantum theoretical mechanism and not by a mere "random walk" as was previously supposed. The original article appeared in Nature but less technical reports have been published in Science Alert and Cosmic Variance.
Some quotes from the Science Alert article:
"Simple single-celled algae use highly sophisticated quantum physics to harvest and convert solar energy for their survival, a new study suggests."
"The water-dwelling algae are in effect highly miniaturised quantum computers, the study suggests. They have mastered the process of photosynthesis so well that they can convert sunlight into electrical energy with near-perfect efficiency."
"They do so by having their light-harvesting proteins "wired" together through a phenomenon known as quantum coherence, enabling them to transfer energy from one protein to another with lightning-fast speed and so reduce energy loss along the energy conversion pathway."
"Photosynthesis makes use of sunlight to convert carbon dioxide into useful biomass and is vital for life on Earth," the paper notes. "Crucial components for the photosynthetic process are antenna proteins, which absorb light and transmit the resultant excitation energy between molecules to a reaction centre."
"The efficiency of these electronic energy transfers has inspired much work on antenna proteins isolated from photosynthetic organisms to uncover the basic mechanisms at play."
"Intriguingly, recent work by other researchers has documented that light-absorbing molecules in some photosynthetic proteins capture and transfer energy according to quantum-mechanical probability laws instead of classical laws at temperatures up to 180 degrees Kelvin."
"Where our study breaks new ground is that we observe the same quantum coherence at normal room temperature," says Professor Curmi. "Therefore it is occurring in living algae."
"It has been assumed that the energy moves from the light-harvesting protein to the reaction centre by a classical 'random walk' - the way a drunk staggers home from the pub. What we have discovered is that instead of the classical random walk, the light-harvesting proteins use quantum mechanical methods to 'test every possible path simultaneously' before picking the correct path to transfer the energy."
More homage to the marvels of photosynthesis can be found on this blog at Chlorophyll Consecration.