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arXiv · 2208.06425

Topological spin excitations in non-Hermitian spin chains with a generalized kernel polynomial algorithm

Guangze Chen·Fei Song·Jose L. Lado
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Abstract

Spectral functions of non-Hermitian Hamiltonians can reveal the existence of topologically non-trivial line gaps and the associated topological edge modes. However, the computation of spectral functions in a non-Hermitian many-body system remains an open challenge. Here, we put forward a numerical approach to compute spectral functions of a non-Hermitian many-body Hamiltonian based on the kernel polynomial method and the matrix-product state formalism. We show that the local spectral functions computed with our algorithm reveal topological spin excitations in a non-Hermitian spin model, faithfully reflecting the non-trivial line gap topology in a many-body model. We further show that the algorithm works in the presence of the non-Hermitian skin effect. Our method offers an efficient way to compute local spectral functions in non-Hermitian many-body systems with tensor-networks, allowing to characterize line gap topology in non-Hermitian quantum many-body models.

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Guangze Chen, Fei Song, Jose L. Lado. 2023-03-09. Topological spin excitations in non-Hermitian spin chains with a generalized kernel polynomial algorithm. https://doi.org/10.1103/physrevlett.130.100401

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