Hilbert-space selected switch of helical edges in an artificial quantum Hall insulator
Abstract
Quantum Hall effects (QHE) host one-dimensional topologically-protected edge channels, which can serve as an essential ingredient in exotic quantum electronic systems. Yet the manual reconstruction of Landau-level topology, by electrostatic confinement or symmetry breaking, remains experimentally challenging. Here, we show that interfacial charge transfer in between CrOCl and large-angle twisted bilayer graphene offsets the two otherwise decoupled Dirac Landau-level ladders in each graphene layer, creating a new sequence of composite filling configurations. At charge neutrality, the composited (+2,−2) state involves only the zeroth Landau levels and becomes fully insulating, with longitudinal resistance reaching the GΩ regime. By contrast, higher composite zero-filling quantum Hall states, including (+6,−6) and (+10,−10), retain counter-propagating helical edge channels and exhibit pronounced non-local transport, reaching up to 50% of the local response. We attribute such switching-behavior to the Landau-spinor Hilbert space -- as the filling is reduced from (+6,−6) to (+2,−2), the orthogonal N=±1 orbital components are removed, eliminating the edge-compatible channel and gapping both bulk and boundary transport. The interaction nature of the observed gapped sates was further examined both experimentally and theoretically. Our results suggest that charge transfer provides a direct route to engineer artificial quantum Hall insulators, opening possibilities for wavefunction-selective control of helical edge modes.
Related
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BibTeX
@misc{ren2026hilbertspace,
title = {{Hilbert-space selected switch of helical edges in an artificial quantum Hall insulator}},
author = {Naijie Ren and Zhiren Xiong and Kaining Yang and Yanran Shi and Hanwen Wang and Kenji Watanabe and Takashi Taniguchi and Neng Wan and Xiaojun Jia and Jianpeng Liu and Zheng Vitto Han and Yaning Wang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.11732},
eprint = {2609.11732},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.11732},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Hilbert-space selected switch of helical edges in an artificial quantum Hall insulator
AU - Naijie Ren
AU - Zhiren Xiong
AU - Kaining Yang
AU - Yanran Shi
AU - Hanwen Wang
AU - Kenji Watanabe
AU - Takashi Taniguchi
AU - Neng Wan
AU - Xiaojun Jia
AU - Jianpeng Liu
AU - Zheng Vitto Han
AU - Yaning Wang
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.11732
UR - https://arxiv.org/abs/2609.11732
AB - Quantum Hall effects (QHE) host one-dimensional topologically-protected edge channels, which can serve as an essential ingredient in exotic quantum electronic systems. Yet the manual reconstruction of Landau-level topology, by electrostatic confinement or symmetry breaking, remains experimentally challenging. Here, we show that interfacial charge transfer in between CrOCl and large-angle twisted bilayer graphene offsets the two otherwise decoupled Dirac Landau-level ladders in each graphene layer, creating a new sequence of composite filling configurations. At charge neutrality, the composited (+2,−2) state involves only the zeroth Landau levels and becomes fully insulating, with longitudinal resistance reaching the GΩ regime. By contrast, higher composite zero-filling quantum Hall states, including (+6,−6) and (+10,−10), retain counter-propagating helical edge channels and exhibit pronounced non-local transport, reaching up to 50% of the local response. We attribute such switching-behavior to the Landau-spinor Hilbert space -- as the filling is reduced from (+6,−6) to (+2,−2), the orthogonal N=±1 orbital components are removed, eliminating the edge-compatible channel and gapping both bulk and boundary transport. The interaction nature of the observed gapped sates was further examined both experimentally and theoretically. Our results suggest that charge transfer provides a direct route to engineer artificial quantum Hall insulators, opening possibilities for wavefunction-selective control of helical edge modes.
ER -