Optical control over topological Chern number in moir\'e materials

Olivier Huber; Kilian Kuhlbrodt; Eric Anderson; Weijie Li; Kenji Watanabe; Takashi Taniguchi; Martin Kroner; Xiaodong Xu; Atac Imamoglu; Tomasz Smolenski

arXiv · 2508.19063

Optical control over topological Chern number in moir\'e materials

Olivier Huber·Kilian Kuhlbrodt·Eric Anderson·Weijie Li·Kenji Watanabe·Takashi Taniguchi·Martin Kroner·Xiaodong Xu·Atac Imamoglu·Tomasz Smolenski

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Abstract

Controlling quantum matter with light offers a promising route to dynamically tune its many-body properties, ranging from band topology to superconductivity. However, achieving such optical control for strongly correlated electron systems in the steady-state has remained elusive. Here, we demonstrate all-optical switching of the spin-valley degree of freedom of itinerant ferromagnets in twisted MoTe2 homobilayers. This system uniquely features flat valley-contrasting Chern bands and exhibits a range of strongly correlated phases at various moir\'e lattice fillings, including Chern insulators and ferromagnetic metals. We show that the spin-valley orientation of all of these phases can be dynamically reversed by resonantly exciting the attractive polaron transition with circularly-polarized light. These findings not only constitute the first direct evidence for non-thermal switching of a ferromagnetic spin state at zero magnetic field, but also demonstrate the possibility of dynamical control over topological order parameter, paving the way for all-optical generation of chiral edge modes and topological quantum circuits.

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Olivier Huber, Kilian Kuhlbrodt, Eric Anderson, Weijie Li, Kenji Watanabe, Takashi Taniguchi, Martin Kroner, Xiaodong Xu, Atac Imamoglu, Tomasz Smolenski. 2025-08-26. Optical control over topological Chern number in moir\'e materials. https://arxiv.org/abs/2508.19063

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