Xinyu Li, Jesse Hagelstein, Felix Sturm, Kateryna Kusyak, Juan I. Aranzadi, Gunda Kipp, Yunfei Huang, Benedikt F. Schulte, Alex M. Potts, Victoria Quirós-Cordero, Chiara Trovatello, Zhi Hao Peng, Chaowei Hu, Jonathan M. DeStefano, Takashi Taniguchi, Kenji Wantanabe, Michael A. Sentef, Dongbin Shin, P. James Schuck, Xiaodong Xu, Jiun-Haw Chu, Hope M. Bretscher, Matthew W. Day, and James W. McIver
Optical Materials Express 15.8 (2025)
Floquet engineering uses time-periodic electromagnetic fields to modify the electronic properties of quantum materials via the creation of Floquet-Bloch states. These photon-dressed states inherit features from both the material and the driving field, enabling the exploration and control of quantum phenomena in light-matter hybrid systems. In non-centrosymmetric materials, shift currents can arise from the quantum geometric properties of electronic wavefunctions. However, shift currents from Floquet-Bloch states remain experimentally unexplored. Here, we employ an on-chip optoelectronic circuit to detect intrinsic terahertz emission from Floquet-Bloch states in Td-WTe2 under intense optical driving. We observe strong edge-localized terahertz emission that scales linearly with the driving field, consistent with the theoretical prediction for shift currents generated by Floquet-Bloch states. The results advance our understanding of strongly driven quantum materials and provide insights for developing efficient, bias-free terahertz sources for future optoelectronic technologies.
