Time & Date: Monday, June 26, 2023, 18:00 CEST
Location: Freihaus Hörsaal 3 at TU Wien (Wiedner Hauptstrasse 8/2nd floor, 1040 Vienna, )
Abstract: Photosynthetic light harvesting of plants and bacteria in vivo is characterized by the remarkable capability of producing electron-hole pairs from absorbed photons with near unit quantum efficiency under ultra-weak illumination conditions. Much experimental and theoretical work using techniques of ultrafast laser spectroscopy has been devoted to analysis of the excited state energy transfer following photoexcitation, but characterization of the initial absorption event has proven elusive. I shall describe a new generation of experimental and theoretical studies using quantum light sources that allow explicit study of the absorption of individual photons. These studies make use of a time-resolved photon counting quantum light spectroscopy (PCQLS) that is based on a heralded single photon source together with coincidence counting. The first experiments reveal a cycle of single photon absorption and single photon fluorescent emission that validates the microscopic interpretation of conventional bulk measurements of quantum efficiency. Associated theoretical studies employing stochastic quantum trajectories conditioned on detection of fluorescent photons reveal the spatio-temporal dynamics of excitations following absorption of single photons with maximal information content. I shall show how these techniques allow a microscopic analysis of the role of excitonic quantum coherence and the influence of vibrational/phonon modes on this, together with a consistent evaluation of the quantum efficiency resulting from absorption of individual photons. Implications for further exploration of the spatio-temporal dynamics of photosynthesis with quantum light sources will be discussed.
Host: Markus Aspelmeyer
Program:
- 18:00 VCQ Student Talk by Caroline Jones
- 18:15 VCQ Colloquium talk by Prof. Whaley
- ***After the talk, drinks & snacks on the roof-top terrace!*** Freihaus, Tower A, 9. OG
