Photon-blockade induced photon anti-bunching in photosynthetic Antennas   with cyclic structures
  One of the important nonclassical effects in quantum optics is the anti-bunching, which has been observed in a large class of physical systems - including light-harvesting antennas with cyclic structures. The units of the ring couple with adjacent ones through dipole-dipole interactions. We show how this strong dipole-dipole interaction leads to photon-blockade resulting in the suppression of double excitation pathway and anti-bunching in photosynthesis systems. The robustness of the photon blockade is demonstrated against the disorder in the ring structures. We hypothesis that the effect may be utilized by light-harvesting systems to avoid damages from excess energy. 
Hui Dong, Sheng-Wen Li, Zhenhuan Yi, Girish S. Agarwal, Marlan O.   Scully
physics.chem-ph physics.bio-ph quant-ph