David Biello in Scientific American:
Plants soak up some of the 1017 joules of solar energy that bathe Earth each second, harvesting as much as 95 percent of it from the light they absorb. The transformation of sunlight into carbohydrates takes place in one million billionths of a second, preventing much of that energy from dissipating as heat. But exactly how plants manage this nearly instantaneous trick has remained elusive. Now biophysicists at the University of California, Berkeley, have shown that plants use the basic principle of quantum computing—the exploration of a multiplicity of different answers at the same time—to achieve near-perfect efficiency.
Biophysicist Gregory Engel and his colleagues cooled a green sulfur bacterium—Chlorobium tepidum, one of the oldest photosynthesizers on the planet—to 77 kelvins [–321 degrees Fahrenheit] and then pulsed it with extremely short bursts of laser light. By manipulating these pulses, the researchers could track the flow of energy through the bacterium's photosynthetic system. “We always thought of it as hopping through the system, the same way that you or I might run through a maze of bushes,” Engel explains. “But, instead of coming to an intersection and going left or right, it can actually go in both directions at once and explore many different paths most efficiently.”
In other words, plants are employing the basic principles of quantum mechanics to transfer energy from chromophore (photosynthetic molecule) to chromophore until it reaches the so-called reaction center where photosynthesis, as it is classically defined, takes place.
More here. [Thanks to Sean Carroll.]