Oscillating anisotropies in a bacteriochlorophyll protein: Evidence for quantum beating between exciton levels

Savikhin, Sergei; Buck, Daniel R.; Struve, Walter S.

doi:10.1016/s0301-0104(97)00223-1

Cited by 154 publications

(194 citation statements)

References 29 publications

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“…Mounting experimental evidence for electronic quantum coherence in photosynthetic energy transfer [1][2][3][4][5] has spawned much debate about both the detailed nature and the biological role of such quantum dynamical features. Quantum coherence is usually encountered in the first, light harvesting stage of photosynthesis.…”

Section: Introductionmentioning

confidence: 99%

“…More generally, can excitonic coherence assist excitation transfer over the uphill steps found in rough energy landscapes? A striking feature of all experiments showing electronic quantum beatings in photosynthesis to date is that they have been performed on small sub-units of light harvesting antenna systems, such as the 7 pigments of the FMO complex [1,2,4] or the 14 pigments in LHC II [5,12]. Yet natural light harvesting antennas are typically composed of hundreds or thousands of pigment molecules organized into many pigment-protein complexes through which energy passes on route to the reaction center [14].…”

Section: Introductionmentioning

confidence: 99%

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Spatial propagation of excitonic coherence enables ratcheted energy transfer

2012

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Experimental evidence shows that a variety of photosynthetic systems can preserve quantum beats in the process of electronic energy transfer, even at room temperature. However, whether this quantum coherence arises in vivo and whether it has any biological function have remained unclear. Here we present a theoretical model that suggests that the creation and recreation of coherence under natural conditions is ubiquitous. Our model allows us to theoretically demonstrate a mechanism for a ratchet effect enabled by quantum coherence, in a design inspired by an energy transfer pathway in the Fenna-Matthews-Olson complex of the green sulfur bacteria. This suggests a possible biological role for coherent oscillations in spatially directing energy transfer. Our results emphasize the importance of analyzing long-range energy transfer in terms of transfer between inter-complex coupling (ICC) states rather than between site or exciton states.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spatial propagation of excitonic coherence enables ratcheted energy transfer

2012

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“…According to the master equation (37), the density matrix in the Q subspace, ρ (Q) (t) ≡ Tr (R) {ρ(t)}, does not experience dissipation. Indeed,…”

Section: Discussionmentioning

confidence: 99%

“…Fundamentally, the master equation offers a plausible explanation of the origins of long-lived coherent optical responses of molecular aggregates in dissipative environments [32][33][34][35][36][37][38][39][40][41].…”

Section: Introductionmentioning

confidence: 99%

Exact quantum master equation for a molecular aggregate coupled to a harmonic bath

2011

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We consider a molecular aggregate consisting of N identical monomers. Each monomer comprises two electronic levels and a single harmonic mode. The monomers interact with each other via dipole-dipole forces. The monomer vibrational modes are bilinearly coupled to a bath of harmonic oscillators. This is a prototypical model for the description of coherent exciton transport, from quantum dots to photosynthetic antennae. We derive an exact quantum master equation for such systems. Computationally, the master equation may be useful for the testing of various approximations employed in theories of quantum transport. Physically, it offers a plausible explanation of the origins of long-lived coherent optical responses of molecular aggregates in dissipative environments.

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“…5,6 The microscopic distinction between the regimes arises from how the bath interacts with the electronic states. While fourwave mixing experiments had been employed to understand coherent and incoherent nuclear motion and energy transfer dynamics in biological systems, 7,8 the development of twodimensional electronic spectroscopy (2DES) has facilitated detailed analysis of four-wave mixing signals by resolving absorption and emission frequencies. [9][10][11][12][13][14][15][16][17] Recent observations of long lived coherences in FMO and reaction center were attributed to electronic states, 8,15 and it was hypothesized that the protein scaffold of the antenna complex protects coherences, through correlated bath fluctuation, to enhance a) Author to whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Towards quantification of vibronic coupling in photosynthetic antenna complexes

Singh

Westberg

Wang

et al. 2015

The Journal of Chemical Physics

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Photosynthetic antenna complexes harvest sunlight and efficiently transport energy to the reaction center where charge separation powers biochemical energy storage. The discovery of existence of long lived quantum coherence during energy transfer has sparked the discussion on the role of quantum coherence on the energy transfer efficiency. Early works assigned observed coherences to electronic states, and theoretical studies showed that electronic coherences could affect energy transfer efficiency-by either enhancing or suppressing transfer. However, the nature of coherences has been fiercely debated as coherences only report the energy gap between the states that generate coherence signals. Recent works have suggested that either the coherences observed in photosynthetic antenna complexes arise from vibrational wave packets on the ground state or, alternatively, coherences arise from mixed electronic and vibrational states. Understanding origin of coherences is important for designing molecules for efficient light harvesting. Here, we give a direct experimental observation from a mutant of LH2, which does not have B800 chromophores, to distinguish between electronic, vibrational, and vibronic coherence. We also present a minimal theoretical model to characterize the coherences both in the two limiting cases of purely vibrational and purely electronic coherence as well as in the intermediate, vibronic regime. C 2015 AIP Publishing LLC. [http://dx

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Oscillating anisotropies in a bacteriochlorophyll protein: Evidence for quantum beating between exciton levels

Cited by 154 publications

References 29 publications

Spatial propagation of excitonic coherence enables ratcheted energy transfer

Spatial propagation of excitonic coherence enables ratcheted energy transfer

Exact quantum master equation for a molecular aggregate coupled to a harmonic bath

Towards quantification of vibronic coupling in photosynthetic antenna complexes

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