title: Quantitative investigations of quantum coherence for a light-harvesting protein at conditions simulating photosynthesis.
abstract: Recent measurements using two-dimensional electronic spectroscopy (2D ES) have shown that the initial dynamic response of photosynthetic proteins can involve quantum coherence. We show how electronic coherence can be differentiated from vibrational coherence in 2D ES. On that basis we conclude that both electronic and vibrational coherences are observed in the phycobiliprotein light-harvesting complex PC645 from Chroomonas sp. CCMP270 at ambient temperature. These light-harvesting antenna proteins of the cryptophyte algae are suspended in the lumen, where the pH drops significantly under sustained illumination by sunlight. Here we measured 2D ES of PC645 at increasing levels of acidity to determine if the change in pH affects the quantum coherence; quantitative analysis reveals that the dynamics are insensitive to the pH change.
authors.affiliation: Department of Chemistry, Institute for Optical Sciences, and Centre for Quantum Information and Quantum Control, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Turner
authors.forename: Rayomond
authors.initials: R
authors.lastname: Dinshaw
authors.forename: Kyung-Koo
authors.initials: KK
authors.lastname: Lee
authors.forename: Michael S
authors.initials: MS
authors.lastname: Belsley
authors.forename: Krystyna E
authors.initials: KE
authors.lastname: Wilk
authors.forename: Paul M G
authors.initials: PM
authors.lastname: Curmi
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Scholes
mesh_terms: D044785:Cryptophyta / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism; D010788:Photosynthesis; D011789:Quantum Theory; D059629:Signal-To-Noise Ratio; D013057:Spectrum Analysis
chemical_list: D045342:Light-Harvesting Protein Complexes