Ultrafast Laser Measurements of Coherences and Entanglement in Light-Harvesting Syste

Photosynthesis proceeds via a first step where cycles of porphyrin molecules absorb visible incoherent light. Using femtosecond pulses one can measure the degree of coherence of the electronic excitations, which are delocalized excitons. Fundamental questions such as preservation of these coherences during energy transfer and diffusion via long range entanglement are current issues requiring measurements on ultrafast time scales.