2013/08/19 by Joel Yuen-Zhou, Yuen-Zhou, Joel, Dylan H. Arias +13
Biochemistry, Genetics and Molecular Biology · Neuroscience · Physics and Astronomy · #FOS: Biological sciences #FOS: Physical sciences #Photoreceptor and optogenetics research #Photosynthetic Processes and Mechanisms #Quantitative Methods (q-bio.QM) #Quantum Physics (quant-ph) #Soft Condensed Matter (cond-mat.soft) #Spectroscopy and Quantum Chemical Studies
paper · pdf · doi:10.48550/arxiv.1308.4566
openalex publication_date 2013/08/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
Long-lived exciton coherences have been recently observed in photosynthetic complexes via ultrafast spectroscopy, opening exciting possibilities for the study and design of coherent exciton transport. Yet, ambiguity in the spectroscopic signals has led to arguments for interpreting them in terms of the exciton dynamics, demanding more stringent tests. We propose a novel strategy, Quantum Process Tomography (QPT) for ultrafast spectroscopy, to reconstruct the evolving quantum state of excitons in double-walled supramolecular light-harvesting nanotubes at room temperature. The protocol calls for eight transient grating experiments with varied pulse spectra. Our analysis reveals unidirectional energy transfer from the outer to the inner wall excitons, absence of nonsecular processes, and an unexpected coherence between those two states lasting about 150 femtoseconds, indicating weak electronic coupling between the walls. Our work constitutes the first experimental QPT in a 'warm' and complex system, and provides an elegant scheme to maximize information from ultrafast spectroscopy experiments.