From Spectral Singularities to Multipartite Entanglement Scaling at Higher-Order Exceptional Points

• URL: http://arxiv.org/abs/2606.24205v1
• Date: Tue, 23 Jun 2026 06:47:34 GMT
• Title: From Spectral Singularities to Multipartite Entanglement Scaling at Higher-Order Exceptional Points
• Abstract summary: We study the scaling behavior of genuine multipartite entanglement in interacting identical-qubit systems.<n>Our results establish a fundamental connection among non-Hermitian degeneracies, multipartite entanglement, and symmetry.
• Score: 2.7961972519572442
• License: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Abstract: Exceptional points (EPs) are non-Hermitian spectral singularities exhibiting fractional-power responses, yet their implications for multipartite entanglement of interacting quantum many-body systems remain largely unexplored. Here we develop a general framework that links higher-order non-Hermitian degeneracies to the scaling behavior of genuine multipartite entanglement in interacting identical-qubit systems. Permutation symmetry of the identical qubits decomposes the exponentially large Hilbert space into independent irreducible-representation sectors, thereby constraining the maximal EP order of $N$ qubits to $N+1$ rather than $2^N$. Near an $n$th-order EP, genuine multipartite entanglement inherits the spectral response and generically exhibits a fractional-power scaling under weak perturbations. Explicit examples show that conventional two-body interactions support third- and fourth-order EPs with the corresponding entanglement responses, whereas higher-order EPs with genuine multipartite-entangled coalesced states require additional independent interaction channels, such as three-body interactions. Our results establish a fundamental connection among non-Hermitian degeneracies, multipartite entanglement, and symmetry, extending higher-order EP physics from spectral singularities to genuine many-body quantum correlations.

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