Periodic Reporting for period 4 - LightNet (LightNet - Tracking the Coherent Light Path in Photosynthetic Networks)
Reporting period: 2020-07-01 to 2021-12-31
Does nature exploit quantum concepts? Does the coherence help to find an optimal path for robust or efficient transfer? How are the coherences sustained? What is their spatial extent in a real light-harvesting network? So far only solutions of complexes were studied, far from the natural network operation, putting on hold conclusions as to a biological role of the coherences.
At the start of this project my group had succeeded in the first detection of coherent oscillations of a single photo-synthetic complex at physiological conditions, and non-classical photon emission of individual complexes. These pioneering results, together with our expertise in nanophotonics, gave the way to address photosynthetic networks in real nano-space and on femtosecond timescale. Specific objectives addressed:
1. Ultrafast single protein detection: tracing the fs coherent energy transfer path of an individual complex; addressing the very nature of the persistent coherences.
2. Beyond fluorescence: light harvesting complex are designed for light transport, not emission. I will explore innovative alternatives: optical antennas to enhance quantum efficiency; detection of stimulated emission; and electrical read-out on graphene.
3. Nanoscale light transport: using local excitation and detection by nanoholes, nanoslits and scanning antenna probes I will spatially map the extent of the inter-complex transfer.
4. The network: combining both coherent fs excitation and localized nanoscale excitation/detection I will track the extent of coherences throughout the network.
The impact of this first exploration of light transport in a nanoscale bionetwork ranges to solar energy management, molecular biology, polymer chemistry and material science.
- Single light harvesting complex excitation spectroscopy
- Room temperature excitation-emission spectra of single LH2 complexes reveal disorder
- Time traces of the anti-bunching [g(2)(0)] and single emitter character on single LH2 complexes
- Spectral phase control has no effects on the emission of single LH2 complexes
- Control of vibronic transition rates by resonant single-molecule-nanoantenna coupling
- Transient ultrafast “encoded” spectroscopy on a single molecule (DBT)
- Stimulated emission microscopy of single emitters (nanocrystals)
- Stimulated emission set-up with sensitivity of 10E-7 differential signal, sufficient to see stimulated emission of individual Quntum dots, yet not of a single organic dye molecule (DBT)
- Closed loop coherent control loop on a single emitter (quantum dot two-photon excitation)
- Spectral phase control of non-linear nanoantenna excitation
- First detection of single FMO complexes at room temperature
- Anti-bunching of single FMO enhanced by resonant nanoantenna
- Photocurrent-detected 2D electronic spectroscopy to reveal energy transfer in light harvesting
- Scanning antenna probe imaging of LH2
- Fabrication of 2-5 nm gap-antennas with the new Zeiss ORION He-ion-microscope
- Room temperature strong coupling (~100meV) of dye molecules and LH2 in antenna nanogaps
- Non-fluorescent, interferometric scattering detection of single proteins with ~15kD sensitivity
- Development of In-line Balanced Interferometric Scattering detection in an associated ERC-PoC project (IBIS)
- Widefield phase imaging to track and discriminate nanoparticles
- Development ultrafast transient holographic microscopy to track nanoparticle fs transients
- Tracking fluorescently labelled vesicles in a cell using interferometric widefield imaging
- Spatio-temporal imaging of light transport on LH nanotubes
- Spatio-temporal mapping of energy diffusion in Au, Si, graphene
- Diffusion of emission in an LH2 membrane, over 300 - 500nm.
Exploitation and dissemination:
The project did result in a patent on interferometric scattering detecting of single proteins, allowing a shot-noise limited sensitivity down to 15kD; the same was supported by an ERC-PoC grant connected to this AdvGrant project.
The project has resulted in around 40 publications (and still a few pending on 2021 research results) in Web-of-Science journals: in Science, Nature NanoTechnol., Nature Phot., Science Adv., Angew.Chem. Adv.Mat. ACSNano, even 11 papers in NanoLetters, 4 in JPC.Lett. etc, etc.…. In parallel the project was presented at many international conferences, workshops, discussion and science management meetings, in total around 60 times. Unfortunately, in the last two years 2020-2021, dissemination was handicapped by COVID, with many scheduled meetings and invitations being canceled. Highlights of the project were picked up in 9 news items and press releases.