Detection Defines Dephasing in Two-Dimensional Electronic Spectroscopy of Materials: Coherent Field Emission versus Incoherent Population Observables
Abstract
The homogeneous spectral linewidth associated with light-matter interactions is a fundamental descriptor of the optical properties of materials, governed by the quantum dynamics of the condensed-matter system. We discuss here that the homogeneous linewidth measured by means of two-dimensional electronic spectroscopy depends not only on the intrinsic microscopic dynamics of the material, but also on the observable through which those dynamics are projected onto the measurement. In this Perspective, we develop a unified framework showing that identical microscopic dynamics can yield different experimentally inferred dephasing times because different detection operators project different sectors of the nonequilibrium dynamics. For coherent emitted-field measurements, the observed linewidth largely retains its conventional connection to the optical coherence time T2. By contrast, in population-detected modalities such as photoluminescence, photocurrent, and other action-detected two-dimensional spectroscopies, the apparent linewidth can additionally encode excited-state population redistribution dynamics, leading naturally to an effective coherence time T2,eff. Using a coupled-mode model propagated under a common Liouvillian, we show that identical microscopic dynamics yield distinct apparent dephasing times when projected onto coherent-emission and population-derived observables. The detection observable is therefore not merely part of the experimental implementation, but determines what dynamical information remains experimentally observable and how homogeneous linewidths should be interpreted as materials descriptors.
Versions
Related
- Resonant photoelectron spectroscopy: a tool for characterising the electronic properties of catalysts in operation
- Electronic Spectroscopy of Atomic Defects in Molybdenum Disulfide under Ambient Conditions
- In Situ Measurement of the Electronic Structure of Oxidized Graphene Employing Quantum-Rate Spectroscopy.
- Probing the electronic origins of heterometallic tuning in platinum complexes by 195Pt NMR spectroscopy
- Population-resolved single-emitter spectroscopy
BibTeX
@misc{paivaortega2026detection,
title = {{Detection Defines Dephasing in Two-Dimensional Electronic Spectroscopy of Materials: Coherent Field Emission versus Incoherent Population Observables}},
author = {Simón Paiva-Ortega and Hao Li and Eric R. Bittner and Carlos Silva-Acuña},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2605.08708},
eprint = {2605.08708},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.08708},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Detection Defines Dephasing in Two-Dimensional Electronic Spectroscopy of Materials: Coherent Field Emission versus Incoherent Population Observables
AU - Simón Paiva-Ortega
AU - Hao Li
AU - Eric R. Bittner
AU - Carlos Silva-Acuña
PY - 2026
DA - 2026/09/04
PB - arXiv
DO - 10.48550/arxiv.2605.08708
UR - https://arxiv.org/abs/2605.08708
AB - The homogeneous spectral linewidth associated with light-matter interactions is a fundamental descriptor of the optical properties of materials, governed by the quantum dynamics of the condensed-matter system. We discuss here that the homogeneous linewidth measured by means of two-dimensional electronic spectroscopy depends not only on the intrinsic microscopic dynamics of the material, but also on the observable through which those dynamics are projected onto the measurement. In this Perspective, we develop a unified framework showing that identical microscopic dynamics can yield different experimentally inferred dephasing times because different detection operators project different sectors of the nonequilibrium dynamics. For coherent emitted-field measurements, the observed linewidth largely retains its conventional connection to the optical coherence time T_2. By contrast, in population-detected modalities such as photoluminescence, photocurrent, and other action-detected two-dimensional spectroscopies, the apparent linewidth can additionally encode excited-state population redistribution dynamics, leading naturally to an effective coherence time T_2,eff. Using a coupled-mode model propagated under a common Liouvillian, we show that identical microscopic dynamics yield distinct apparent dephasing times when projected onto coherent-emission and population-derived observables. The detection observable is therefore not merely part of the experimental implementation, but determines what dynamical information remains experimentally observable and how homogeneous linewidths should be interpreted as materials descriptors.
ER -