Coherences in Molecular Excitation with Natural Incoherent Light?

Seminar
Speaker
Paul Brumer Department of Chemistry and Centre for Quantum INformation and Quantum Control University of Toronto
Date
21/05/2014 - 15:00Add to Calendar 2014-05-21 15:00:00 2014-05-21 15:00:00 Coherences in Molecular Excitation with Natural Incoherent Light? 2D photon echo studies on light harvesting systems have generated considerable interest and controversy regarding  the possible role of quantum coherence effects in biological systems. As we have previously shown, such studies rely on the response of molecular systems to pulsed laser excitation, which is  dramatically different than the response to natural incoherent light. Significantly, the latter produces mixed stationary states, devoid of time dependent coherences. If this would be ``the whole  story", then the observed coherences are essentially irrelevant. We will describe the origin of the above result and then discuss recent developments in this area, including (a) the importance of various  decoherence time scales for reaching stationary states in natural incoherent light, (b) the role of doorway states in the molecular response, and (c) the significance of long lived coherences associated with Agarwal-Fano resonances. Examples will be chosen from basic three level V-systems, dynamics in large molecules, and Rydberg atoms interacting with the cosmic microwave background. The significance of the results for natural light harvesting systems will be emphasized. seminar room on the 9th floor of the Nanobuilding המחלקה לפיזיקה physics.dept@mail.biu.ac.il Asia/Jerusalem public
Place
seminar room on the 9th floor of the Nanobuilding
Abstract

2D photon echo studies on light harvesting systems
have generated considerable interest and controversy regarding 
the possible role of quantum coherence effects in biological systems.
As we have previously shown, such studies rely on the response of
molecular systems to pulsed laser excitation, which is 
dramatically different than the response to natural incoherent
light. Significantly, the latter produces mixed stationary states,
devoid of time dependent coherences. If this would be ``the whole 
story", then the observed coherences are essentially irrelevant.

We will describe the origin of the above result and then discuss recent
developments in this area, including (a) the importance of various 
decoherence time scales for reaching stationary states in natural incoherent
light, (b) the role of doorway states in the molecular response, and (c) the
significance of long lived coherences associated with Agarwal-Fano resonances.
Examples will be chosen from basic three level V-systems,
dynamics in large molecules, and Rydberg atoms
interacting with the cosmic microwave background. The significance of the
results for natural light harvesting systems will be emphasized.

תאריך עדכון אחרון : 13/05/2014