Studies of photosynthetic systems exhibit quantum coherence mechanisms Eric Beitia Low-Dimensional Physics 2nd term University of Basque Country Dr. Angel Rubio

Contents Introduction Photosynthesis - Basic concepts and illustrations - Biological process Quantum Coherence - Entanglement - Quantum superposition Method of detection - 2-D electron spectroscopy - Quantum beats - Measurements Future works - Application - What can we learn?

Introduction ‘’Nature does not know of good and evil, it only knows of balance’’ Dr. Walter Bishop, FOX television show ‘Fringe’ Understanding nature in this form is a century long ongoing research project

Photosynthesis Photo – Light Synthesis – Putting together Sunlight, most important and abundant source of energy Light reaction center Mapping routes What is the efficiency of the direction it takes? Why or how did it decide to take that route?

Fenna-Matthews-Olsen Complex FMO Complex Green Sulfur Bacteria Manages the light harvesting mechanism of light through the rest of the organism Transfer of energy (Photon) from an ‘Antenna’ (chlorosome) To the reaction center which distributes unto the rest of the Organism Behaves as a quantum wire, where we typically have ballistic transport (Mean free path is much greater than the width of the wire)

Quantum Coherence Entanglement - Particles even molecules, interact and are then separated, end up in a quantum state that is undetermined until MEASURED - Until measured all particle involved in the interaction are in a quantum superposition - No classical analogue. Purely quantum mechanical phenomenon - Detected by quantum beats using 2-D electrons spectroscopy

Entanglement

2-D Electron Spectroscopy Peaks represent interference patterns, quantum beats Interference patterns are the routes of the energy states since it would be difficult to map in real time, snapshots are taken at different femtoseconds of interaction Due to the uncertainty principle routes cannot be isolated but it is evident that there multiple routes Phase evolution of excitonic states are observed through the beats

Quantum Beats What is being looked at to understand is the efficiency of the light harvesting mechanism of the photosynthesis model. Quantum electrodynamics can explain the behavior of what is found to be the source of this efficiency The source being quantum coherence of many paths being mapped before choosing the shortest path to it’s destination

Math of quantum beats As we know by orthogonality that is 1 while is zero Which means that the path the A atom decay can be recognized while in the V atom it cannot Creation operator Annihilation operator Beat note term for V type atom Beat note term for A type atom

Quantum Beats

Future works To learn the optimal route for photosynthetic process To harness the ability for synthetic systems, such as solar light harvesting Discover further evidence of quantum effects unto the microscopic world To further understand quantum coherence to be applied to macroscopic systems To be able to take what we learn and apply it to other biological processes, i.e. neuroscience, brain function, and disease prevention In depth study on mean free path of excitonic energy transfer

References Patrick F. Tekavec, Jeffrey A. Myers, Optics Letter, Vol. 34, No. 9, May 1, 2009 K. Birgitta Whaley, Mohan Sarovar, arX1v: v1 [quant-ph] 18 Dec 2010 Gregory S. Engel, ScienceDirect, Procedia Chemistry 3 (2011) Gregory S. Engel, Tessa R. Calhoun, Vol 446, 12 April 2007, doi: /nature05678