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arXiv · 1910.10946

$\mathcal{PT}$-Symmetric Topological Edge-Gain Effect

Alex Y. Song·Xiao-Qi Sun·Avik Dutt·Momchil Minkov·Casey Wojcik·Haiwen Wang·Ian Williamson·Meir Orenstein·Shanhui Fan
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Abstract

We demonstrate a non-Hermitian topological effect that is characterized by having complex eigenvalues only in the edge states of a topological material, despite the fact that the material is completely uniform. Such an effect can be constructed in any topological structure formed by two gapped sub-systems, e.g., a quantum spin-Hall system, with a suitable non-Hermitian coupling between the spins. The resulting complex-eigenvalued edge state is robust against defects due to the topological protection. In photonics, such an effect can be used for the implementation of topological lasers, in which a uniform pumping provides gain only in the edge lasing state. Furthermore, such a topological lasing model is reciprocal and is thus compatible with standard photonic platforms.

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Alex Y. Song, Xiao-Qi Sun, Avik Dutt, Momchil Minkov, Casey Wojcik, Haiwen Wang, Ian Williamson, Meir Orenstein, Shanhui Fan. 2019-10-24. $\mathcal{PT}$-Symmetric Topological Edge-Gain Effect. https://doi.org/10.1103/physrevlett.125.033603

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