Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems


Photosynthetic complexes are exquisitely tuned to capture solar light efficiently, and then transmit the excitation energy to reaction centres, where long term energy storage is initiated. The energy transfer mechanism is often described by semiclassical models that invoke ‘hopping’ of excited-state populations along discrete energy levels1,2. Two-dimensional Fourier transform electronic spectroscopy3,4,5 has mapped6 these energy levels and their coupling in the Fenna–Matthews–Olson (FMO) bacteriochlorophyll complex, which is found in green sulphur bacteria and acts as an energy ‘wire’ connecting a large peripheral light-harvesting antenna, the chlorosome, to the reaction centre7,8,9. The spectroscopic data clearly document the dependence of the dominant energy transport pathways on the spatial properties of the excited-state wavefunctions of the whole bacteriochlorophyll complex6,10. But the intricate dynamics of quantum coherence, which has no classical analogue, was largely neglected in the analyses—even though electronic energy transfer involving oscillatory populations of donors and acceptors was first discussed more than 70 years ago11, and electronic quantum beats arising from quantum coherence in photosynthetic complexes have been predicted12,13 and indirectly observed14. Here we extend previous two-dimensional electronic spectroscopy investigations of the FMO bacteriochlorophyll complex, and obtain direct evidence for remarkably long-lived electronic quantum coherence playing an important part in energy transfer processes within this system. The quantum coherence manifests itself in characteristic, directly observable quantum beating signals among the excitons within the Chlorobium tepidum FMO complex at 77 K. This wavelike characteristic of the energy transfer within the photosynthetic complex can explain its extreme efficiency, in that it allows the complexes to sample vast areas of phase space to find the most efficient path.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Two-dimensional electronic spectra of FMO.
Figure 2: Electronic coherence beating.
Figure 3: Characteristic anticorrelation between peak amplitude and width.
Figure 4: Quantum beating in cross peaks.

Similar content being viewed by others


  1. Blankenship, R. E. Molecular Mechanisms of Photosynthesis (Blackwell Science, Oxford/Malden, 2002)

    Book  Google Scholar 

  2. van Amerongen, H., Valkunas, L. & van Grondelle, R. Photosynthetic Excitons (World Scientific, Singapore/River Edge, 2000)

    Book  Google Scholar 

  3. Brixner, T., Mančal, T., Stiopkin, I. V. & Fleming, G. R. Phase-stabilized two-dimensional electronic spectroscopy. J. Chem. Phys. 121, 4221–4236 (2004)

    Article  ADS  CAS  Google Scholar 

  4. Jonas, D. M. Two-dimensional femtosecond spectroscopy. Annu. Rev. Phys. Chem. 54, 425–463 (2003)

    Article  ADS  CAS  Google Scholar 

  5. Cowan, M. L., Ogilvie, J. P. & Miller, R. J. D. Two-dimensional spectroscopy using diffractive optics based phased-locked photon echoes. Chem. Phys. Lett. 386, 184–189 (2004)

    Article  ADS  CAS  Google Scholar 

  6. Brixner, T. et al. Two-dimensional spectroscopy of electronic couplings in photosynthesis. Nature 434, 625–628 (2005)

    Article  ADS  CAS  Google Scholar 

  7. Fenna, R. E. & Matthews, B. W. Chlorophyll arrangement in a bacteriochlorophyll protein from Chlorobium limicola. Nature 258, 573–577 (1975)

    Article  ADS  CAS  Google Scholar 

  8. Li, Y. F., Zhou, W. L., Blankenship, R. E. & Allen, J. P. Crystal structure of the bacteriochlorophyll a protein from Chlorobium tepidum. J. Mol. Biol. 271, 456–471 (1997)

    Article  CAS  Google Scholar 

  9. Camara-Artigas, A., Blankenship, R. E. & Allen, J. P. The structure of the FMO protein from Chlorobium tepidum at 2.2 angstrom resolution. Photosynth. Res. 75, 49–55 (2003)

    Article  CAS  Google Scholar 

  10. Cho, M. H. et al. Exciton analysis in 2D electronic spectroscopy. J. Phys. Chem. B 109, 10542–10556 (2005)

    Article  CAS  Google Scholar 

  11. Perrin, F. Thoérie quantique des transferts d'activation entre molécules de même espèce. Cas des solutions fluorescentes. Ann. Phys. (Paris) 17, 283–314 (1932)

    ADS  CAS  MATH  Google Scholar 

  12. Knox, R. S. Electronic excitation transfer in the photosynthetic unit: Reflections on work of William Arnold. Photosynth. Res. 48, 35–39 (1996)

    Article  CAS  Google Scholar 

  13. Leegwater, J. A. Coherent versus incoherent energy transfer and trapping in photosynthetic antenna complexes. J. Phys. Chem. 100, 14403–14409 (1996)

    Article  CAS  Google Scholar 

  14. Savikhin, S., Buck, D. R. & Struve, W. S. Oscillating anisotropies in a bacteriochlorophyll protein: Evidence for quantum beating between exciton levels. Chem. Phys. 223, 303–312 (1997)

    Article  CAS  Google Scholar 

  15. Brixner, T., Stiopkin, I. V. & Fleming, G. R. Tunable two-dimensional femtosecond spectroscopy. Opt. Lett. 29, 884–886 (2004)

    Article  ADS  CAS  Google Scholar 

  16. Cho, M. H. & Fleming, G. R. The integrated photon echo and solvation dynamics. II. Peak shifts and two-dimensional photon echo of a coupled chromophore system. J. Chem. Phys. 123, 114506 (2005)

    Article  ADS  Google Scholar 

  17. Pisliakov, A. V., Mančal, T. & Fleming, G. R. Two-dimensional optical three-pulse photon echo spectroscopy. II. Signatures of coherent electronic motion and exciton population transfer in dimer two-dimensional spectra. J. Chem. Phys. 124, 234505 (2006)

    Article  ADS  Google Scholar 

  18. Abramavicius, D., Valkunas, L. & van Grondelle, R. Exciton dynamics in ring-like photosynthetic light-harvesting complexes: A hopping model. Phys. Chem. Chem. Phys. 6, 3097–3105 (2004)

    Article  CAS  Google Scholar 

  19. Renger, T., May, V. & Kuhn, O. Ultrafast excitation energy transfer dynamics in photosynthetic pigment-protein complexes. Phys. Rep. Rev. Phys. Lett. 343, 138–254 (2001)

    Google Scholar 

  20. Jang, S. J., Newton, M. D. & Silbey, R. J. Multichromophoric Forster resonance energy transfer. Phys. Rev. Lett. 92, 9312–9323 (2004)

    Google Scholar 

  21. Novoderezhkin, V., Wendling, M. & van Grondelle, R. Intra- and interband transfers in the b800-b850 antenna of Rhodospirillum molischianum: Redfield theory modeling of polarized pump-probe kinetics. J. Phys. Chem. B 107, 11534–11548 (2003)

    Article  CAS  Google Scholar 

  22. Vulto, S. I. E. et al. Excited state dynamics in FMO antenna complexes from photosynthetic green sulfur bacteria: A kinetic model. J. Phys. Chem. B 103, 8153–8161 (1999)

    Article  CAS  Google Scholar 

  23. Potts, D. & Kunis, S. Stability results for scattered data interpolation by trigonometric polynomials. 〈〉 (2007)

  24. Dreyer, J., Moran, A. M. & Mukamel, S. Tensor components in three pulse vibrational echoes of a rigid dipeptide. Bull. Korean Chem. Soc. 24, 1091–1096 (2003)

    Article  CAS  Google Scholar 

  25. Hochstrasser, R. M. Two-dimensional IR-spectroscopy: polarization anisotropy effects. Chem. Phys. 266, 273–284 (2001)

    Article  CAS  Google Scholar 

  26. Kempe, J. Quantum random walks: An introductory overview. Contemp. Phys. 44, 307–327 (2003)

    Article  ADS  Google Scholar 

  27. Grover, L. K. Quantum mechanics helps in searching for a needle in a haystack. Phys. Rev. Lett. 79, 325–328 (1997)

    Article  ADS  CAS  Google Scholar 

  28. Joo, T., Jia, Y. W. & Fleming, G. R. Ti-sapphire regenerative amplifier for ultrashort high-power multikilohertz pulses without an external stretcher. Opt. Lett. 20, 389–391 (1995)

    Article  ADS  CAS  Google Scholar 

  29. Lepetit, L., Cheriaux, G. & Joffre, M. Linear techniques of phase measurement by femtosecond spectral interferometry for applications in spectroscopy. J. Opt. Soc. Am. B 12, 2467–2474 (1995)

    Article  ADS  CAS  Google Scholar 

  30. Frigo, M. & Johnson, S. G. The design and implementation of fftw3. Proc. IEEE 93, 216–231 (2005)

    Article  Google Scholar 

Download references


We thank D. Zigmantas for discussions and J. Wen for purification of the sample. This work was supported by the DOE (at LBNL, UC Berkeley and Washington Univ.). G.S.E. thanks the Miller Institute for Basic Research in Science for support. T.-K.A. was supported by the Korea Research Foundation Grant funded by the Korean government (MOEHRD).

Author Contributions G.S.E, T.R.C., T.-K.A. and E.L.R. prepared the cryogenic sample and collected the data; G.S.E., E.L.R, T.M. and Y.-C.C. performed the data analysis. R.E.B. grew, isolated and purified the FMO sample. G.S.E. wrote the paper, and all authors discussed the results and commented on the manuscript. G.R.F. provided guidance throughout the experiment and analysis and helped to write the manuscript.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Graham R. Fleming.

Ethics declarations

Competing interests

Reprints and permissions information is available at The authors declare no competing financial interests.

Supplementary information

Supplementary Figures

This file contains Supplementary Figures 1-2 with Legends and Supplementary Movie Legend. (PDF 850 kb)

Supplementary Movie 1

This file contains Supplementary Movie 1. The Supplementary Movie shows spectral evolution of the FMO 2D Electronic spectra with ultrafast time resolution. Data from 33 time points is linearly interpolated to create this movie. (MOV 12750 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Engel, G., Calhoun, T., Read, E. et al. Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems. Nature 446, 782–786 (2007).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing