Speaker
Description
Hybrid exciton in moiré superlattices of two-dimensional semiconductors inherits the electric dipole and strong moiré trapping from its interlayer component, whereas the local stacking registries at the trapping sites determine its intralayer component to have either an s-wave or a p-wave envelope function, MoTe2 moire bilayer being an example for the latter. This talk will explore the cooperative electrodynamics in a periodic array of moire excitons. The Hermitian and anti-Hermitian parts of the dipole Green’s function correspond respectively to the non-radiative (Forster type) dipole-dipole coupling, and cooperative radiative decay that leads to superradiant and subradiant states. Moiré excitons with a p-wave-envelope intralayer component has a remarkably long radiative lifetime, whereas Forster coupling in the near field allows their coherent hopping when kinetic propagation is suppressed. Valley-flip hopping channels are found as significant as the valley-conserving ones, leading to rich possibilities to tailor valley-orbit-couplings and non-trivial topology of the moiré exciton and biexciton superlattice. We further show that the many-body exciton ground state is a mixture of atomic-type and molecular-type BEC due to the interplay of inter-sublattice dipole attraction and intra-sublattice repulsion, featuring unique superradiant properties.
The works are supported by the National Natural Science Foundation of China (No. 12425406), the Research Grant Council of Hong Kong (AoE/P-701/20, HKU SRFS2122-7S05, A-HKU705/21), and New Cornerstone Science Foundation.
References
[1] Huiyuan Zheng, Ci Li, Hongyi Yu and Wang Yao, Förster valley-orbit coupling and topological lattice of hybrid moiré excitons,, Comm. Phys. 8, 193 (2025)
[2] Haochen Wang and Wang Yao, Emergent Kagome lattice and non-Abelian lattice gauge field of biexcitons in t-MoTe2, Natl. Sci. Rev. 13, nwaf328 (2026).
[3] Haowei Xu, Wang Yao, and Ju Li, Exotic Cooperative Quantum Optics of Moire Exciton Superlattices, arXiv:2603.06998, PRL in press.
[4] Haochen Wang, Shengxian Li, Hongyu Lu, Mingxing Chen and Wang Yao, in preparation