A long-standing mystery of photosynthesis is how the process converts sunlight with nearly 100 percent efficiency to chemical energy. The key may be quantum coherence, the same phenomenon that makes lasers and superconductors work. Researchers at the University of California, Berkeley, investigated purple bacteria, where an ensemble of pigments and proteins absorbs light and channels its energy into chemicals. Components of this complex oscillate after they get excited with light, and these excitations are kept synchronized by specific vibrations of the protein connecting these components, like well-timed pushes on a swing to keep it in motion. This coherence makes the ensemble act together as a “supermolecule” of sorts, rapidly settling on the most efficient energy pathway. The research, in the June 8 Science, could improve designs for solar cells and other synthetic light-harvesting devices.