Experimental demonstration of angular momentum-dependent topological transport using a transmission line network.

Jiang, Tianshu; Xiao, Meng; Chen, Wen-Jie; Yang, Lechen; Fang, Yawen; Tam, Wing Yim; Chan, C T · Nat Commun · 2019

basic_science · Level V

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Abstract

Novel classical wave phenomenon analogs of the quantum spin Hall effect are mostly based on the construction of pseudo-spins. Here we show that the non-trivial topology of a system can also be realized using orbital angular momentum through a coupling between the angular momentum and the wave vector. The idea is illustrated with a tight-binding model and experimentally demonstrated with a transmission line network. We show experimentally that even a very small network cluster exhibits angular momentum-dependent one-way topological edge states, and their properties can be described in terms of local Chern numbers. Our work provides a new mechanism to realize counterparts of the quantum spin Hall effect in classical waves and may offer insights for other systems.