Dynamical signatures of the Yang-Lee edge singularity in non-Hermitian systems

Abstract

The Yang-Lee edge singularity is an intriguing critical phenomenon characterized by nonunitary field theory. However, its experimental realization for interacting many-body systems remains elusive. We show that Yang-Lee edge singularities, regarded as many-body exceptional points, can be observed using both the self-normal and the associated-biorthogonal Loschmidt echoes, leveraging the advantages of nonunitary dynamics in non-Hermitian systems. The Loschmidt echoes are demonstrated to display unitary dynamics in the $\mathcal{P}\mathcal{T}$-symmetric regime but exhibit nonunitary dynamics in the $\mathcal{P}\mathcal{T}$ symmetry-broken regime, leading to a sharp change near an exceptional point. We hereby identify exceptional points in both the non-Hermitian transverse field Ising model and the Yang-Lee model, and determine the critical exponent that is consistent with nonunitary conformal field theory. This work provides a direct observation of Yang-Lee edge singularities in non-Hermitian many-body systems arising from nonunitary dynamics.

8 pages, 4 figures and 2 tables

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Cited by in corpus (4)

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• Characterizing the Yang-Lee zeros of the classical Ising model through dynamic quantum phase transitions
• Survival of Hermitian Criticality in the Non-Hermitian Framework
• Anatomy of Non-Hermitian Dynamical Quantum Phase Transitions