title: Observation of an Excitonic Quantum Coherence in CdSe Nanocrystals.
abstract: Recent observations of excitonic coherences within photosynthetic complexes suggest that quantum coherences could enhance biological light harvesting efficiencies. Here, we employ optical pump-probe spectroscopy with few-femtosecond pulses to observe an excitonic quantum coherence in CdSe nanocrystals, a prototypical artificial light harvesting system. This coherence, which encodes the high-speed migration of charge over nanometer length scales, is also found to markedly alter the displacement amplitudes of phonons, signaling dynamics in the non-Born-Oppenheimer regime.
authors.affiliation: Division of Chemistry and Biological Chemistry, and Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, Singapore 637371, Singapore.
authors.forename: Shuo
authors.initials: S
authors.lastname: Dong
authors.affiliation: Department of Physics and Astronomy, University of Rochester , Rochester, New York 14627, United States.
authors.forename: Dhara
authors.initials: D
authors.lastname: Trivedi
authors.affiliation: Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Sabyasachi
authors.initials: S
authors.lastname: Chakrabortty
authors.affiliation: Advanced Ultrafast Laser Research Center, The University of Electro-Communications , 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan.|JST, CREST, K'Gobancho , 7 Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan.|Department of Electrophysics, National Chiao-Tung University , Hsinchu 300, Taiwan.|Institute of Laser Engineering, Osaka University , 2-6 Yamada-oka, Suita, Osaka 565-0971, Japan.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore.|Institute of Materials Research & Engineering, A*STAR , 3 Research Link, Singapore 117602, Singapore.
authors.forename: Yinthai
authors.initials: Y
authors.lastname: Chan
authors.affiliation: Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States.
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Prezhdo
authors.affiliation: Division of Chemistry and Biological Chemistry, and Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, Singapore 637371, Singapore.
authors.forename: Zhi-Heng
authors.initials: ZH
authors.lastname: Loh
keywords: Electronic coherence; charge migration; electron−phonon coupling; femtosecond optical spectroscopy; non-Born−Oppenheimer dynamics; quantum dots