Paper detail

Space and space-time topologies in a type-II hyperbolic lattice

Recent breakthroughs in hyperbolic lattices have expanded the study of topological phases of matter from Euclidean to non-Euclidean spaces. However, prior work has mostly focused on spatial topological states at the single outer edge of type-I hyperbolic lattices. The dynamic transfer of hyperbolic topological states across multiple edges, as well as the emergence of spatiotemporal topological phenomena, remains largely unexplored. Here, we establish both spatial and spatiotemporal topologies in a newly discovered type-II hyperbolic lattice possessing outer and inner edges. Using electric circuits, we experimentally realize a type-II hyperbolic Chern insulator and directly observe degenerate chiral edge states of opposite chirality at its outer and inner edges. Furthermore, by coupling these counter-propagating chiral edge states, we demonstrate an anti-time-parity phase transition, enabling dynamic transfer between them in arbitrary proportions. Finally, we propose a novel paradigm for constructing a (2+1)-dimensional hyperbolic space-time crystal, which hosts an intertwined topology of spatial Chern and temporal winding numbers, resulting in a unique space-time topological string state. Our work expands the frontier of hyperbolic topological physics, paving the way for the spatiotemporal dynamic manipulation of hyperbolic topological states.