  Photosynthesis is remarkable, achieving near unity light harvesting quantum
efficiency in spite of dynamic light conditions and noisy physiological
environment. Under these adverse conditions, it remains unknown whether there
exists a fundamental organizing principle that gives rise to robust
photosynthetic light harvesting. Here, we present a noise-canceling network
model that relates noisy physiological conditions, power conversion efficiency,
and the resulting absorption spectrum of photosynthetic organisms. Taking
external light conditions in three distinct niches - full solar exposure, light
filtered by oxygenic phototrophs, and under sea water - we derive optimal
absorption characteristics for efficient solar power conversion. We show how
light harvesting antennae can be finely tuned to maximize power conversion
efficiency by minimizing excitation noise, thus providing a unified theoretical
basis for the experimentally observed wavelength dependence of light absorption
in green plants, purple bacteria, and green sulfur bacteria.
