Letter

Nature 463, 644-647 (4 February 2010) | doi:10.1038/nature08811; Received 14 July 2009; Accepted 17 December 2009

Coherently wired light-harvesting in photosynthetic marine algae at ambient temperature

Elisabetta Collini1,3,4, Cathy Y. Wong1,3, Krystyna E. Wilk2, Paul M. G. Curmi2, Paul Brumer1 & Gregory D. Scholes1

  1. Department of Chemistry, Institute for Optical Sciences and Centre for Quantum Information and Quantum Control, University of Toronto, 80 St George Street, Toronto, Ontario, M5S 3H6 Canada
  2. School of Physics and Centre for Applied Medical Research, St Vincent’s Hospital, The University of New South Wales, Sydney, New South Wales 2052, Australia
  3. These authors contributed equally to this work.
  4. Present address: Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35100, Padova, Italy.

Correspondence to: Gregory D. Scholes1 Correspondence and requests for materials should be addressed to G.D.S. (Email: gscholes@chem.utoronto.ca).

Photosynthesis makes use of sunlight to convert carbon dioxide into useful biomass and is vital for life on Earth. Crucial components for the photosynthetic process are antenna proteins, which absorb light and transmit the resultant excitation energy between molecules to a reaction centre. The efficiency of these electronic energy transfers has inspired much work on antenna proteins isolated from photosynthetic organisms to uncover the basic mechanisms at play1, 2, 3, 4, 5. Intriguingly, recent work has documented6, 7, 8 that light-absorbing molecules in some photosynthetic proteins capture and transfer energy according to quantum-mechanical probability laws instead of classical laws9 at temperatures up to 180K. This contrasts with the long-held view that long-range quantum coherence between molecules cannot be sustained in complex biological systems, even at low temperatures. Here we present two-dimensional photon echo spectroscopy10, 11, 12, 13 measurements on two evolutionarily related light-harvesting proteins isolated from marine cryptophyte algae, which reveal exceptionally long-lasting excitation oscillations with distinct correlations and anti-correlations even at ambient temperature. These observations provide compelling evidence for quantum-coherent sharing of electronic excitation across the 5-nm-wide proteins under biologically relevant conditions, suggesting that distant molecules within the photosynthetic proteins are ‘wired’ together by quantum coherence for more efficient light-harvesting in cryptophyte marine algae.

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