TY - JOUR
T1 - Efficient Modeling of Organic Chromophores for Entangled Two-Photon Absorption
AU - Kang, Gyeongwon
AU - Nasiri Avanaki, Kobra
AU - Mosquera, Martín A.
AU - Burdick, Ryan K.
AU - Villabona-Monsalve, Juan P.
AU - Goodson, Theodore
AU - Schatz, George C.
N1 - Funding Information:
G.K., M.M., T.G., and G.C.S. were supported by NSF Eager Grant CHE-1836392 (for two-photon research), and K.A. and G.C.S. were supported by NSF Grant CHE-1760537 (for entangled emission and absorption). This manuscript is dedicated to the memory of Richard P. Van Duyne, who recently passed away.
Publisher Copyright:
Copyright © 2020 American Chemical Society.
PY - 2020/6/10
Y1 - 2020/6/10
N2 - The use of a nonclassical light source for studying molecular electronic structure has been of great interest in many applications. Here we report a theoretical study of entangled two-photon absorption (ETPA) in organic chromophores, and we provide new insight into the quantitative relation between ETPA and the corresponding unentangled TPA based on the significantly different line widths associated with entangled and unentangled processes. A sum-over-states approach is used to obtain classical TPA and ETPA cross sections and to explore the contribution of each electronic state to the ETPA process. The transition moments and energies needed for this calculation were obtained from a second linear-response (SLR) TDDFT method [J. Chem. Phys., 2016, 144, 204105], which enables the treatment of relatively large polythiophene dendrimers that serve as two-photon absorbers. In addition, the SLR calculations provide estimates of the excited state radiative line width, which we relate to the entangled two-photon density of states using a quantum electrodynamic analysis. This analysis shows that for the dendrimers being studied, the line width for ETPA is orders of magnitude narrower than for TPA, corresponding to highly entangled photons with a large Schmidt number. The calculated cross sections are in good agreement with the experimentally reported values. We also carried out a state-resolved analysis to unveil pathways for the ETPA process, and these demonstrate significant interference behavior. We emphasize that the use of entangled photons in TPA process plays a critical role in probing the detailed electronic structure of a molecule by probing light-matter interference nature in the quantum limit.
AB - The use of a nonclassical light source for studying molecular electronic structure has been of great interest in many applications. Here we report a theoretical study of entangled two-photon absorption (ETPA) in organic chromophores, and we provide new insight into the quantitative relation between ETPA and the corresponding unentangled TPA based on the significantly different line widths associated with entangled and unentangled processes. A sum-over-states approach is used to obtain classical TPA and ETPA cross sections and to explore the contribution of each electronic state to the ETPA process. The transition moments and energies needed for this calculation were obtained from a second linear-response (SLR) TDDFT method [J. Chem. Phys., 2016, 144, 204105], which enables the treatment of relatively large polythiophene dendrimers that serve as two-photon absorbers. In addition, the SLR calculations provide estimates of the excited state radiative line width, which we relate to the entangled two-photon density of states using a quantum electrodynamic analysis. This analysis shows that for the dendrimers being studied, the line width for ETPA is orders of magnitude narrower than for TPA, corresponding to highly entangled photons with a large Schmidt number. The calculated cross sections are in good agreement with the experimentally reported values. We also carried out a state-resolved analysis to unveil pathways for the ETPA process, and these demonstrate significant interference behavior. We emphasize that the use of entangled photons in TPA process plays a critical role in probing the detailed electronic structure of a molecule by probing light-matter interference nature in the quantum limit.
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U2 - 10.1021/jacs.0c02808
DO - 10.1021/jacs.0c02808
M3 - Article
C2 - 32401020
AN - SCOPUS:85086354483
VL - 142
SP - 10446
EP - 10458
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 23
ER -