近日，瑞士巴塞尔大学T. Smoleński团队研究了光子材料拓扑陈氏数的光学控制。相关论文于2026年1月28日发表在《自然》杂志上。

利用光调控量子物质为动态调控其多体性质——从能带拓扑到超导特性——开辟了前景广阔的途径。然而，对强关联电子系统实现稳态下的此类光学调控仍面临挑战。

研究组展示了在扭曲二硫化钼（t-MoTe2）同质双层中对巡游铁磁体自旋-谷自由度的光控切换。该体系独特地具备平坦的谷反差陈能带，并在不同莫尔晶格填充下呈现包括陈绝缘体与铁磁金属在内的多种强关联相。结果发现，通过圆偏振光共振激发激子-极化子跃迁，可动态反转所有这些物相的自旋-谷取向。这些发现不仅为零磁场下铁磁自旋态的非热光控切换提供了直接证据，更证实了对拓扑序参量进行动态调控的可能性，为光学产生手性边缘模和构建拓扑量子电路开辟了道路。

附：英文原文

Title: Optical control over topological Chern number in moiré materials

Author: Huber, O., Kuhlbrodt, K., Anderson, E., Li, W., Watanabe, K., Taniguchi, T., Kroner, M., Xu, X., Imamolu, A., Smoleski, T.

Issue&Volume: 2026-01-28

Abstract: Controlling quantum matter with light offers a promising route to dynamically tune its many-body properties, ranging from band topology1,2 to superconductivity3. However, achieving such optical control for strongly correlated electron systems in the steady state has remained elusive. Here we demonstrate optical switching of the spin–valley degree of freedom of itinerant ferromagnets in twisted MoTe2 (t-MoTe2) homobilayers. This system uniquely features flat valley-contrasting Chern bands and exhibits a range of strongly correlated phases at various moiré lattice fillings, including Chern insulators and ferromagnetic metals4,5,6,7. We show that the spin–valley orientation of all of these phases can be dynamically reversed by resonantly exciting the exciton–polaron8 transitions with circularly polarized light. These findings not only provide direct evidence for non-thermal optical switching of a ferromagnetic spin state at zero magnetic field but also demonstrate the possibility of dynamical control over a topological order parameter, paving the way for optical generation of chiral edge modes and topological quantum circuits.

DOI: 10.1038/s41586-025-09851-w

Source: https://www.nature.com/articles/s41586-025-09851-w