Energy’s secrets may lie in garden

Berkeley scientists have found that light-loving bacteria — and probably plants — rely on quantum physics to turn sunlight into usable energy rapidly and efficiently, overturning the standard explanation for how green living things get their energy.

Armed with those quantum secrets, scientists could see faster progress in copying nature’s machinery and harnessing the sun for human use.
So far, they’ve been hampered by reliance on the classic explanation of photosynthesis, taught widely in high school and college classrooms. It says that sunlight excites one molecule of chlorophyll after another, the energy hopping step-by-step in random search of a place to release an electron

for conversion into chemical energy for the plant.

But that’s only half the story and hardly the elegant half, according to scientists at Lawrence Berkeley National Laboratory and the University of California, Berkeley.

In the British journal Nature on Thursday, they reported detecting quantum waves of energy exploring all possible excitation states in a bacterial protein at the same time.

“The effect is like if you’re trying to run in a maze but instead of having to choose which way to go, you could choose to go several ways at once,” said lead author Gregory Engel, an ultra-fast laser spectroscopist and chemist at the Berkeley lab.

Adding quantum mechanics makes scientists’ thinking about photosynthesis more complex but also complete. That better understanding boosts the likelihood that researchers can move beyond traditional semiconductor-based solar cells to more efficient artificial photosynthetic devices based, as in nature, on pigments and proteins.

“First we have to learn how nature is doing it then we can learn how to do it,” said Fromme of Arizona State University. “In principle, they don’t mimic nature at present.”

Inside Bay Area