Light-matter dynamics in topological quantum materials enables ultralow-power, ultrafast devices. A challenge is simulating multiple field and particle equations for light, electrons, and atoms over vast spatiotemporal scales on Exaflop/s computers with increased heterogeneity and low-precision focus. We present a paradigm shift that solves the multiscale/multiphysics/heterogeneity challenge harnessing hardware heterogeneity and low-precision arithmetic. Divide-conquer-recombine algorithms divide the problem into not only spatial but also physical subproblems of small dynamic ranges and minimal mutual information, which are mapped onto best-characteristics-matching hardware units, while metamodel-space algebra minimizes communication and precision requirements. Using 60,000 GPUs of Aurora, DC-MESH (divide-and-conquer Maxwell-Ehrenfest-surface hopping) and XS-NNQMD (excited-state neural-network quantum molecular dynamics) modules of MLMD (multiscale light-matter dynamics) software were 152- and 3,780-times faster than the state-of-the-art for 15.4 million-electron and 1.23 trillion-atom PbTiO3 material, achieving 1.87 EFLOP/s for the former. This enabled the first study of light-induced switching of topological superlattices for future ferroelectric 'topotronics'.
@article{arxiv.2509.00966,
title = {Multiscale light-matter dynamics in quantum materials: from electrons to topological superlattices},
author = {Taufeq Mohammed Razakh and Thomas Linker and Ye Luo and Nariman Piroozan and John Pennycook and Nalini Kumar and Albert Musaelian and Anders Johansson and Boris Kozinsky and Rajiv K. Kalia and Priya Vashishta and Fuyuki Shimojo and Shinnosuke Hattori and Ken-ichi Nomura and Aiichiro Nakano},
journal= {arXiv preprint arXiv:2509.00966},
year = {2025}
}