Life directly or indirectly depends on the light-harvesting processes. Plants, algae, and photosynthetic bacteria possess highly efficient light-harvesting systems, transforming light energy into the required form of the chemical energy. In natural light-harvesting systems, an antenna absorbs photons, which are transferred to a reaction center through an exciton transfer complex. The research into highly efficient funneling of excitation energy in these natural complexes is also important for the design of highly efficient organic solar devices. The Fenna-Matthews-Olsen (FMO) complex which is found in green sulfur bacteria is one of the most well-studied exciton transfer complexes because of its near-unity efficiency, small size, and simplicity.