Abstract

Quantum control of photochemistry exploits molecular interferences by adjusting the phases of multiple quantum pathways to different product channels via adapted excitation light. Experiments implement a learning loop in which molecular feedback iteratively refines the excitation pulse until an optimum solution directs the photoreaction towards a desired channel [1]. So far, feedback control has been absent from the world of biology. Furthermore, only few examples have proven explicitly the role of molecular coherence. Here we report feedback-optimised coherent control of biological function, namely regulation of the energy flow pathways in the 125 kDa light-harvesting antenna complex LH2 from Rhodospeudomonas acidophila, a photosynthetic purple bacterium.

© 2002 Optical Society of America