Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session D05: Electronic-Vibrational Coupling in Light Harvesting I. Photosynthetic Light HarvestingFocus
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Sponsoring Units: DCP DAMOP DCMP DPOLY Chair: Jacob Krich, Univ of Ottawa Room: 111 |
Monday, March 2, 2020 2:30PM - 2:42PM |
D05.00001: Investigating the Energy Transfer Dynamics in the Baseplate of Green Photosynthetic Bacteria using 2D Electronic Spectroscopy Alexa Rae Carollo, Carrie Goodson, Robert E. Blankenship, Niels-Ulrik Frigaard, Donatas Zigmantas The structure of the baseplate, a pigment-protein complex that mediates energy transfer in green photosynthetic bacteria, is not fully understood. The baseplate cannot be isolated from the chlorosome light harvesting antenna, but their spectral signatures can be separated with femtosecond two-dimensional electronic spectroscopy (2DES)[1]. In this work, 2D spectra of the baseplate in a mutant of Chlorobaculum tepidum, which was previously found to contain dimeric pigments[2], will be compared to 2D spectra of Chloroflexus aurantiacus to characterize the pigment interactions and energy transfer pathways in both samples. |
Monday, March 2, 2020 2:42PM - 2:54PM |
D05.00002: Probing quantum coherence in photosynthetic energy transfer in the presence of fluctuating environment with levitons and time-dependent nonequilibrium Green functions Priyanka Mondal, Branislav Nikolic, Alexander Eisfeld The first few steps of photosynthesis in light harvesting complexes involve creation of exciton at chlorosome and its transport to reaction center, where the charge separation takes place. The transport of exciton from chlorosome to reaction center is highly efficient but the role of long-lived quantum coherence towards this efficiency is highly debatable. Here we present a prototype that uses a leviton voltage pulse to map a single exciton entering Fenna-Matthews-Olson pigment complex which is mapped as coupled quantum dots with attached leads, in presence of environmental fluctuation coming from molecular dynamics simulation. Our main result includes long-lived quantum beating in population dynamics and the dependency of quantum dephasing on exciton transport efficiency in fluctuating environment using time-dependent nonequilibrium Green functions approach. |
Monday, March 2, 2020 2:54PM - 3:30PM |
D05.00003: Exploring electronic-vibrational coupling in chlorophylls and photosynthetic complexes by polarization-controlled 2D electronic spectroscopy Invited Speaker: Donatas Zigmantas Electronic-vibrational (vibronic) coupling has been suggested to play an important role in energy transfer and charge separation processes in photosynthesis. It is, however, highly elusive phenomenon to investigate. To this end we have employed polarization-controlled 2DES together with advanced Fourier analysis [1]. We use double-crossed polarization scheme, which extracts signals generated by excitation of coherences, involving transitions with different orientation of dipole moments. It allows for studying electronic and vibronically mixed coherences, and therefore enables to directly detect the presence of vibronic mixing (coupling). |
Monday, March 2, 2020 3:30PM - 3:42PM |
D05.00004: Matrix-product-state-based calculations of exciton-phonon dynamics for light-harvesting complexes R. Kevin Kessing, Salvatore Manmana, Jianshu Cao Excitonic systems with one to a few dozen sites are an important topic in contexts such as quantum optics, molecular spectroscopy or the dynamics of light-harvesting complexes. However, the dynamics are often strongly influenced by coupling to the external or internal vibrational modes, which presents a computationally much more challenging problem. We investigate the dynamics of excitonic oligomers with such non-perturbative coupling to a quantum bath using a symmetry-adapted state-of-the-art matrix-product-state (MPS) code[1] which has not been previously applied to this type of system. Using this accurate, unbiased method, we focus on studying spreading, coherence and entanglement behavior. The insights gained from these analyses help us better understand exciton dynamics in photosynthesis, e.g. in the purple bacteria light-harvesting complex LH2, which exhibits efficient energy transfer and a notable symmetric structure. [2] |
Monday, March 2, 2020 3:42PM - 4:18PM |
D05.00005: Vibronic Structure and Coherence in the Bacterial Reaction Center Invited Speaker: Jennifer Ogilvie Much of our current understanding of photosynthetic charge separation has been derived from studies of the bacterial reaction center (BRC) from purple bacteria. We report two-dimensional electronic spectroscopy (2DES) experiments on the BRC that reveal previously hidden excitonic and vibronic structure. Through analysis of the coherent dynamics of the BRC and careful comparison with monomeric bacteriochlorophyll we report vibronic coherence and identify resonances between a number of key intramolecular pigment vibrations and electronic energy gaps in the BRC. Such resonances have been proposed to play a functional role in photosynthetic energy transfer and charge separation. |
Monday, March 2, 2020 4:18PM - 4:30PM |
D05.00006: Modeling Exciton Transport in the Photosystem II Reaction Center via the Modified Generalized Quantum Master Equation Kristina Lenn, Ellen Mulvihill, Xing Gao, Alexander Schubert, Eitan Geva
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Monday, March 2, 2020 4:30PM - 4:42PM |
D05.00007: The Coherence Time of Sunlight Berke Ricketti, Erik Gauger, Alessandro Fedrizzi The discovery that quantum coherence might enhance biological processes such as photosynthesis is not only of fundamental importance but also leads to hopes of developing bio-inspired ‘green’ quantum technologies that mimic nature. A key question is how the time scale of coherent processes in molecular systems compare to that of the driving light source — the sun. Across the community, the coherence time quoted for sunlight spans at least two orders of magnitude, ranging from 0.6 to >10 of femtoseconds. This difference can potentially be significant in deciding whether the induced light-matter coherence is long enough to affect macro system behaviour. Here we revisit the historic calculations of sunlight coherence starting with the blackbody spectrum and then proceed to provide values for the more realistic case of atmospherically filtered light. We corroborate these values with interferometric measurements of atmospherically filtered sunlight in the visible spectrum, the wavelength range most relevant for photosynthetic organisms on Earth. This is the first step in our development of a novel sunlight emulator utilizing a train of ultrafast laser pulses. |
Monday, March 2, 2020 4:42PM - 4:54PM |
D05.00008: Quantum coherence in a photosynthetic dimer driven by incoherent sunlight Pei-Yun Yang, Jianshu Cao In this work, we demonstrate noise-induced coherence in a model of a photosynthetic molecular dimer driven by an incoherent radiation field. Through perturbation theory associated with white noise approximation, the dynamics of the excitons is characterized by the dressed exciton states. The exciton coherence exhibits respectively quantum beats among the exciton states and quasistationary relaxation processes in two opposite parameter limits. We further examine the steady-state physics, where the exciton coherence can be classified into light-induced and trap-induced coherences that break detailed balance. At last, the steady-state population and energy fluxes in the dimer system are discussed. |
Monday, March 2, 2020 4:54PM - 5:30PM |
D05.00009: Carotenoid-mediated light harvesting in plants
Minjung Son, Gabriela Schlau-Cohen Invited Speaker: Gabriela Schlau-Cohen Plants absorb across the visible region of the solar spectrum followed by rapid and efficient collection of the photoenergy in lower-lying states. Previous experiments have been limited to the dynamics of the low-energy states, leaving the higher-energy states, including how they transfer energy downhill, unexplored. We describe ultrabroadband 2D electronic spectroscopy that enables us to map out the excited states and dynamics of the major antenna complex of plants across the visible region. By analyzing the vibrational wavepackets in the spectra, we identify a debated dark state on a single carotenoid, lutein 2, that mediates relaxation. This result reveals that the protein binding pocket controls the electronic structure of carotenoids, and therefore their function in photosynthesis. |
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