Dark states in quantum photosynthesis

A model of quantum photosynthesis with degeneracy in the light-harvesting system is discussed. We consider interaction of excitons in chromophores with light and phonons (vibrations of environment). These interactions have dipole form but are different (are related to non–parallel vectors of “bright” states). We show that this leads to excitation of non-decaying “dark” states. We discuss relation of this model to the known from spectroscopical experiments phenomenon of existence of photonic echo in quantum photosynthesis.