Incoherent dark excitons extend Floquet-like physics across time and momentum
Abstract
Floquet phenomena - where a coherent, time-periodic drive hybridizes the conduction band with energy-replicated copies of the valence band - have been demonstrated with intense optical fields and, more recently, other bosonic excitations. However, within mean-field approximations and the current understanding of Floquet phenomena, these effects survive only for the coherence time of the drive, limiting practical use and current demonstrations to the sub-picosecond regime. Here, consistent with recent theoretical predictions beyond the mean-field picture, using time- and angle-resolved photoemission spectroscopy in WSe2/MoS2 heterostructures, we show that incoherent, dense populations of dark interlayer excitons hybridize the conduction band with energy-replicated copies of the valence band, mimicking Floquet-like phenomena - now persisting for nearly a nanosecond. With increasing interlayer exciton density, the valence band and its replica evolve from an inverted-parabolic to a Mexican-hat dispersion, a signature of the predicted non-zero static coupling that hybridizes the bands and scales linearly with the exciton density. By tuning twist angle, we further show that dark excitons with net momentum create replicas that hybridize with bands offset not just in energy but also in momentum, providing another powerful degree of freedom beyond conventional Floquet engineering. These results establish a robust, long-lived route to engineering electronic states, beyond a coherent, zero-momentum drive.
Related
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- Self-Trapping Enabled Highly Bright Momentum-Indirect Interlayer Excitons
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BibTeX
@misc{zhu2026incoherent,
title = {{Incoherent dark excitons extend Floquet-like physics across time and momentum}},
author = {Xing Zhu and Jacques Hawecker and Enrico Perfetto and Vivek Pareek and David R. Bacon and Harley Suchiang and Nanami Tomoda and Amrita Mitra and Takumi Fukuda and Sebastien Roux and Ouri Karni and Jack Featherstone and Kenji Watanabe and Takashi Taniguchi and Michael K. L. Man and Julien Madéo and Felipe H. da Jornada and Gianluca Stefanucci and Keshav M. Dani},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.38156},
eprint = {2610.38156},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.38156},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Incoherent dark excitons extend Floquet-like physics across time and momentum
AU - Xing Zhu
AU - Jacques Hawecker
AU - Enrico Perfetto
AU - Vivek Pareek
AU - David R. Bacon
AU - Harley Suchiang
AU - Nanami Tomoda
AU - Amrita Mitra
AU - Takumi Fukuda
AU - Sebastien Roux
AU - Ouri Karni
AU - Jack Featherstone
AU - Kenji Watanabe
AU - Takashi Taniguchi
AU - Michael K. L. Man
AU - Julien Madéo
AU - Felipe H. da Jornada
AU - Gianluca Stefanucci
AU - Keshav M. Dani
PY - 2026
DA - 2026/10/28
PB - arXiv
DO - 10.48550/arxiv.2610.38156
UR - https://arxiv.org/abs/2610.38156
AB - Floquet phenomena - where a coherent, time-periodic drive hybridizes the conduction band with energy-replicated copies of the valence band - have been demonstrated with intense optical fields and, more recently, other bosonic excitations. However, within mean-field approximations and the current understanding of Floquet phenomena, these effects survive only for the coherence time of the drive, limiting practical use and current demonstrations to the sub-picosecond regime. Here, consistent with recent theoretical predictions beyond the mean-field picture, using time- and angle-resolved photoemission spectroscopy in WSe_2/MoS_2 heterostructures, we show that incoherent, dense populations of dark interlayer excitons hybridize the conduction band with energy-replicated copies of the valence band, mimicking Floquet-like phenomena - now persisting for nearly a nanosecond. With increasing interlayer exciton density, the valence band and its replica evolve from an inverted-parabolic to a Mexican-hat dispersion, a signature of the predicted non-zero static coupling that hybridizes the bands and scales linearly with the exciton density. By tuning twist angle, we further show that dark excitons with net momentum create replicas that hybridize with bands offset not just in energy but also in momentum, providing another powerful degree of freedom beyond conventional Floquet engineering. These results establish a robust, long-lived route to engineering electronic states, beyond a coherent, zero-momentum drive.
ER -