2020/04/29 by Guangwei Hu, Qingdong Ou, Guangyuan Si +9 · 18 citations
Materials Science · Physics and Astronomy · #2D Materials and Applications #Strong Light-Matter Interactions #Topological Materials and Phenomena #cond-mat.mes-hall #physics.optics
paper · pdf · doi:10.1038/s41586-020-2359-9
published as Nature, Vol 582, pp 209-213 (2020) · Nature, in press
arxiv created 2020/04/29 · crossref issued 2020/06/11 · crossref published 2020/06/11 · crossref published-online 2020/06/11 · crossref published-print 2020/06/11 · openalex publication_date 2020/06/11 · crossref created 2020/06/11 · arxiv updated 2020/06/15 · openalex created_date 2020/06/19 · crossref deposited 2023/05/20 · crossref indexed 2026/07/29 · openalex updated_date 2026/07/30
Twisted two-dimensional bi-layers offer exquisite control on the electronic bandstructure through the interlayer rotation and coupling, enabling magic-angle flat-band superconductivity and moiré excitons. Here, we demonstrate how analogous principles, combined with large anisotropy, enable extreme control and manipulation of the photonic dispersion of phonon polaritons (PhPs) in van der Waals (vdW) bi-layers. We experimentally observe tunable topological transitions from open (hyperbolic) to closed (elliptic) dispersion contours in twisted bi-layered α-MoO3 at photonic magic angles, induced by polariton hybridization and robustly controlled by a topological quantity. At these transitions the bilayer dispersion flattens, exhibiting low-loss tunable polariton canalization and diffractionless propagation with resolution below λ0/40. Our findings extend twistronics and moiré physics to nanophotonics and polaritonics, with great potential for nano-imaging, nanoscale light propagation, energy transfer and quantum applications.