title: Quantum coherent energy transfer over varying pathways in single light-harvesting complexes.
abstract: The initial steps of photosynthesis comprise the absorption of sunlight by pigment-protein antenna complexes followed by rapid and highly efficient funneling of excitation energy to a reaction center. In these transport processes, signatures of unexpectedly long-lived coherences have emerged in two-dimensional ensemble spectra of various light-harvesting complexes. Here, we demonstrate ultrafast quantum coherent energy transfer within individual antenna complexes of a purple bacterium under physiological conditions. We find that quantum coherences between electronically coupled energy eigenstates persist at least 400 femtoseconds and that distinct energy-transfer pathways that change with time can be identified in each complex. Our data suggest that long-lived quantum coherence renders energy transfer in photosynthetic systems robust in the presence of disorder, which is a prerequisite for efficient light harvesting.
authors.affiliation: ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, Castelldefels, Barcelona, Spain.
authors.forename: Richard
authors.initials: R
authors.lastname: Hildner
authors.forename: Daan
authors.initials: D
authors.lastname: Brinks
authors.forename: Jana B
authors.initials: JB
authors.lastname: Nieder
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Cogdell
authors.forename: Niek F
authors.initials: NF
authors.lastname: van Hulst
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D025541:Bacteriochlorophyll A / Q000737:chemistry*; D004735:Energy Transfer; D005583:Fourier Analysis; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry*; D010788:Photosynthesis; D011789:Quantum Theory; D012241:Rhodopseudomonas / Q000737:chemistry*; D013696:Temperature
chemical_list: C081521:B800-850 light-harvesting complex, bacteria; D001426:Bacterial Proteins; D025541:Bacteriochlorophyll A; D045342:Light-Harvesting Protein Complexes