title: A critical view on transport and entanglement in models of photosynthesis.
abstract: We revisit critically the recent claims, inspired by quantum optics and quantum information, that there is entanglement in the biological pigment-protein complexes, and that it is responsible for the high transport efficiency. While unexpectedly long coherence times were experimentally demonstrated, the existence of entanglement is, at the moment, a purely theoretical conjecture; it is this conjecture that we analyse. As demonstrated by a toy model, a similar transport phenomenology can be obtained without generating entanglement. Furthermore, we also argue that, even if entanglement does exist, it is purely incidental and seems to play no essential role for the transport efficiency. We emphasize that our paper is not a proof that entanglement does not exist in light-harvesting complexes-this would require a knowledge of the system and its parameters well beyond the state of the art. Rather, we present a counter-example to the recent claims of entanglement, showing that the arguments, as they stand at the moment, are not sufficiently justified and hence cannot be taken as a proof for the existence of entanglement, let alone of its essential role, in the excitation transport.
authors: Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Technikerstrasse 21A, 6020 Innsbruck, Austria. markus.tiersch@uibk.ac.at
authors: Markus
authors: M
authors: Tiersch
authors: Sandu
authors: S
authors: Popescu
authors: Hans J
authors: HJ
authors: Briegel
mesh_terms: D004735:Energy Transfer / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000502:physiology* / Q000528:radiation effects; D008954:Models, Biological; D008956:Models, Chemical; D010788:Photosynthesis / Q000502:physiology* / Q000528:radiation effects; D011789:Quantum Theory
chemical_list: D045342:Light-Harvesting Protein Complexes