Competing skin effect and quasiperiodic localization in the non-Hermitian Su-Schrieffer-Heeger chain: Reentrant delocalization, spectral topology destruction, and entanglement suppression

• URL: http://arxiv.org/abs/2603.20330v1
• Date: Fri, 20 Mar 2026 06:17:43 GMT
• Title: Competing skin effect and quasiperiodic localization in the non-Hermitian Su-Schrieffer-Heeger chain: Reentrant delocalization, spectral topology destruction, and entanglement suppression
• Abstract summary: We investigate the interplay between the non-Hermitian skin effect and Aubry-André-Harper quasiperiodic disorder in a one-dimensional Su-Schrieffer-Heeger chain.<n>We show that quasiperiodic disorder unwinds the complex spectral loops, destroying the point-gap topology at a critical strength.<n>We also show that the skin effect suppresses entanglement entropy to near-zero values while sufficiently strong AAH disorder partially restores it.
• Score: 0.5307735857768683
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We investigate the interplay between the non-Hermitian skin effect and Aubry-André-Harper (AAH) quasiperiodic disorder in a one-dimensional Su-Schrieffer-Heeger (SSH) chain with nonreciprocal hopping. By exact diagonalization, transfer-matrix analysis, and an analytical similarity-transformation argument, we map the full ( , $δ$) phase diagram, where A is the AAH modulation strength and the nonreciprocity parameter. We identify five distinct regimes: ( ) topological with extended bulk, (II) AAH-localized, (III) skin-localized, (IV) fully localized, and a previously unreported (V) competition regime exhibiting reentrant partial delocalization, in which intermediate quasiperiodic disorder disrupts the directional skin accumulation before ultimately Anderson-localizing all states. Using phase-averaged diagnostics and finite-size scaling, we confirm that the reentrant regime is robust, characterized by a non-monotonic inverse participation ratio that sharpens with increasing system size. We derive an analytical expression for the modified localization boundary $λ_{c}(δ)=2\sqrt{v_{eff}w}$ with $v_{vff}=\sqrt{v^{2}-δ^{2}}$, which agrees with numerical Lyapunov exponent calculations. We further show that quasiperiodic disorder progressively unwinds the complex spectral loops, destroying the point-gap topology at a critical strength distinct from the band-topological transition ; that the skin effect suppresses entanglement entropy to near-zero values while sufficiently strong AAH disorder partially restores it ; and that the SSH sublattice structure absent in the widely studied non-Hermitian AAH chain is essential for producing the five-phase landscape, as demonstrated by direct comparison with the non-dimerized limit.

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