Optical Access to Dark Excitons Via Spin-Phonon Fano Interference.
4 affiliations
- 1Department of Physics, TU Dortmund University, Dortmund, Germany.
- 2Ioffe Institute, St. Petersburg, Russia.
- 3Experimental Physics VI, Faculty of Physics and Astronomy, Ruhr University Bochum, Bochum, Germany.
- 4Dortmund Center for Advanced Exploration of Dynamics Across Limits Using Spectroscopy (DAEDALUS), TU Dortmund University, Dortmund, Germany.
Abstract
Spin-dark excitons in semiconductor nanostructures are inherently optically silent: angular-momentum selection rules forbid their radiative recombination, granting long lifetimes attractive for quantum information storage and excitonic condensation, but placing their energy structure and bright-dark coupling beyond standard optical spectroscopy. Established access routes rely on symmetry-lowering perturbations, dedicated single-emitter device fabrication, or near-field methods, each of which perturbs the states under study or excludes ensembles. Here, we show that a Fano-type quantum interference between two acoustic-phonon scattering pathways, consisting of a resonant spin-flip process coupling bright and dark excitons and a non-resonant inelastic process sharing the same acoustic phonon mode, opens an optical window onto the dark exciton in unperturbed ensembles of (In,Ga)As/GaAs quantum dots. The interference manifests as antiresonance and bipolar spectral profiles whose shape and position encode the bright-dark exciton coupling, are tunable through magnetic-field orientation, optical pumping intensity, and temperature, and persist to about 40 K, with a characteristic thermal scale of about 5 meV. The same lineshape analysis reveals a sign reversal of the exciton exchange energy at excited quantum-dot shells. Relying only on exchange-split exciton states and acoustic phonons, the mechanism should transfer to two-dimensional transition metal dichalcogenides and perovskite nanocrystals, where dark excitons play a central role.
Related
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BibTeX
@article{schindler2026optical,
title = {{Optical Access to Dark Excitons Via Spin-Phonon Fano Interference.}},
author = {Janina J Schindler and Katja Barthelmi and Mikhail M Glazov and Carlo Sgroi and Sven Scholz and Arne Ludwig and Andreas D Wieck and Jörg Debus},
journal = {Advanced science (Weinheim, Baden-Wurttemberg, Germany)},
year = {2026},
month = oct,
doi = {10.1002/advs.78207},
url = {https://europepmc.org/article/MED/42875814},
note = {CC BY},
}
RIS
TY - JOUR
TI - Optical Access to Dark Excitons Via Spin-Phonon Fano Interference.
AU - Janina J Schindler
AU - Katja Barthelmi
AU - Mikhail M Glazov
AU - Carlo Sgroi
AU - Sven Scholz
AU - Arne Ludwig
AU - Andreas D Wieck
AU - Jörg Debus
PY - 2026
DA - 2026/10/14
JO - Advanced science (Weinheim, Baden-Wurttemberg, Germany)
DO - 10.1002/advs.78207
UR - https://europepmc.org/article/MED/42875814
AB - Spin-dark excitons in semiconductor nanostructures are inherently optically silent: angular-momentum selection rules forbid their radiative recombination, granting long lifetimes attractive for quantum information storage and excitonic condensation, but placing their energy structure and bright-dark coupling beyond standard optical spectroscopy. Established access routes rely on symmetry-lowering perturbations, dedicated single-emitter device fabrication, or near-field methods, each of which perturbs the states under study or excludes ensembles. Here, we show that a Fano-type quantum interference between two acoustic-phonon scattering pathways, consisting of a resonant spin-flip process coupling bright and dark excitons and a non-resonant inelastic process sharing the same acoustic phonon mode, opens an optical window onto the dark exciton in unperturbed ensembles of (In,Ga)As/GaAs quantum dots. The interference manifests as antiresonance and bipolar spectral profiles whose shape and position encode the bright-dark exciton coupling, are tunable through magnetic-field orientation, optical pumping intensity, and temperature, and persist to about 40 K, with a characteristic thermal scale of about 5 meV. The same lineshape analysis reveals a sign reversal of the exciton exchange energy at excited quantum-dot shells. Relying only on exchange-split exciton states and acoustic phonons, the mechanism should transfer to two-dimensional transition metal dichalcogenides and perovskite nanocrystals, where dark excitons play a central role.
SN - 2198-3844
ER -