Unsupervised Learning of Topological Non-Abelian Braiding in Non-Hermitian Bands

Fuente: arXiv
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Main Authors: Long, Yang, Xue, Haoran, Zhang, Baile
Format: Preprint
Published: 2024
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author Long, Yang
Xue, Haoran
Zhang, Baile
author_facet Long, Yang
Xue, Haoran
Zhang, Baile
contents The topological classification of energy bands has laid the groundwork for the discovery of various topological phases of matter in recent decades. While this classification has traditionally focused on real-energy bands, recent studies have revealed the intriguing topology of complex-energy, or non-Hermitian bands. For example, the spectral winding of complex-energy bands can from unique topological structures like braids, holding promise for advancing quantum computing. However, discussions of complex-energy braids have been largely limited to the Abelian braid group $\mathbb{B}_2$ for its relative simplicity, while identifying topological non-Abelian braiding is still difficult since it has no universal topological invariant for characterization. Here, we present a machine learning algorithm for the unsupervised identification of non-Abelian braiding of multiple complex-energy bands. The consistency with Artin's well-known topological equivalence conditions in braiding is demonstrated. Inspired by the results from unsupervised learning, we also introduce a winding matrix as a topological invariant in charactering the braiding topology and unveiling the bulk-edge correspondence of non-Abelian braided non-Hermitian bands. Finally, we extend our approach to identify non-Abelian braiding topology in 2D/3D exceptional semimetals and successfully address the unknotting problem in an unsupervised manner.
format Preprint
id arxiv_https___arxiv_org_abs_2401_17968
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Unsupervised Learning of Topological Non-Abelian Braiding in Non-Hermitian Bands
Long, Yang
Xue, Haoran
Zhang, Baile
Mesoscale and Nanoscale Physics
Data Analysis, Statistics and Probability
The topological classification of energy bands has laid the groundwork for the discovery of various topological phases of matter in recent decades. While this classification has traditionally focused on real-energy bands, recent studies have revealed the intriguing topology of complex-energy, or non-Hermitian bands. For example, the spectral winding of complex-energy bands can from unique topological structures like braids, holding promise for advancing quantum computing. However, discussions of complex-energy braids have been largely limited to the Abelian braid group $\mathbb{B}_2$ for its relative simplicity, while identifying topological non-Abelian braiding is still difficult since it has no universal topological invariant for characterization. Here, we present a machine learning algorithm for the unsupervised identification of non-Abelian braiding of multiple complex-energy bands. The consistency with Artin's well-known topological equivalence conditions in braiding is demonstrated. Inspired by the results from unsupervised learning, we also introduce a winding matrix as a topological invariant in charactering the braiding topology and unveiling the bulk-edge correspondence of non-Abelian braided non-Hermitian bands. Finally, we extend our approach to identify non-Abelian braiding topology in 2D/3D exceptional semimetals and successfully address the unknotting problem in an unsupervised manner.
title Unsupervised Learning of Topological Non-Abelian Braiding in Non-Hermitian Bands
topic Mesoscale and Nanoscale Physics
Data Analysis, Statistics and Probability
url https://arxiv.org/abs/2401.17968