Carrier-Resolved Attosecond Valley Polarimetry of Monolayer MoS2
Abstract
In recent years, all-optical writing and switching of valley polarization in two-dimensional semiconductors has been demonstrated on femtosecond timescales. Reading this polarization out on the same timescale, carrier by carrier, has so far remained out of reach. Employing semiconductor Bloch equation simulations of monolayer MoS2, we show that attosecond transient absorption closes this gap by turning the Mo 4p semicore edge into a quantitative valley polarimeter. We find that pump-enabled core-to-valence absorption probes the holes while core-to-conduction bleaching probes the electrons, so that a single spectrum identifies each carrier by its photoabsorption energy. The hole channel, Pauli-blocked in equilibrium, emerges background-free. Its circular dichroism reverses sign with the pump helicity, and its normalized magnitude is proportional to the valley polarization. Finally, we show that scanning the probe delay clocks the few-femtosecond write in real time. Thus, attosecond core-level dichroism is a carrier-sensitive, quantitative probe of the creation and evolution of valley polarization.
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BibTeX
@misc{rana2026carrierresolved,
title = {{Carrier-Resolved Attosecond Valley Polarimetry of Monolayer MoS$_2$}},
author = {Navdeep Rana and Lun Yue and Mette B. Gaarde},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.25121},
eprint = {2608.25121},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.25121},
}
RIS
TY - UNPB
TI - Carrier-Resolved Attosecond Valley Polarimetry of Monolayer MoS_2
AU - Navdeep Rana
AU - Lun Yue
AU - Mette B. Gaarde
PY - 2026
DA - 2026/08/25
PB - arXiv
DO - 10.48550/arxiv.2608.25121
UR - https://arxiv.org/abs/2608.25121
AB - In recent years, all-optical writing and switching of valley polarization in two-dimensional semiconductors has been demonstrated on femtosecond timescales. Reading this polarization out on the same timescale, carrier by carrier, has so far remained out of reach. Employing semiconductor Bloch equation simulations of monolayer MoS_2, we show that attosecond transient absorption closes this gap by turning the Mo 4p semicore edge into a quantitative valley polarimeter. We find that pump-enabled core-to-valence absorption probes the holes while core-to-conduction bleaching probes the electrons, so that a single spectrum identifies each carrier by its photoabsorption energy. The hole channel, Pauli-blocked in equilibrium, emerges background-free. Its circular dichroism reverses sign with the pump helicity, and its normalized magnitude is proportional to the valley polarization. Finally, we show that scanning the probe delay clocks the few-femtosecond write in real time. Thus, attosecond core-level dichroism is a carrier-sensitive, quantitative probe of the creation and evolution of valley polarization.
ER -