Direct Measurement of Topological Properties of an Exceptional Parabola

Weiyuan Tang, Kun Ding, Guancong Ma

Research output: Contribution to journalArticlepeer-review

Abstract

Non-Hermitian systems can produce branch singularities known as exceptional points (EPs). Different from singularities in Hermitian systems, the topological properties of an EP can involve either the winding of eigenvalues that produces a discriminant number (DN) or the eigenvector holonomy that generates a Berry phase. The multiplicity of topological invariants also makes non-Hermitian topology richer than its Hermitian counterpart. Here, we study a parabola-shaped trajectory formed by EPs with both theory and acoustic experiments. By obtaining both the DNs and Berry phases through the measurement of eigenvalues and eigenfunctions, we show that the EP trajectory endows the parameter space with a nontrivial fundamental group. Our findings not only shed light on exotic non-Hermitian topology but also provide a route for the experimental characterization of non-Hermitian topological invariants.

Original languageEnglish
Article number034301
JournalPhysical Review Letters
Volume127
Issue number3
DOIs
Publication statusPublished - 15 Jul 2021

Scopus Subject Areas

  • Physics and Astronomy(all)

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