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arXiv · 2609.06799

Scale-Free Localization Morphing in Bilocally Coupled Hatano-Nelson Chains

Chong Wang·Linhu Li
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Abstract

We investigate an anomalous critical non-Hermitian skin effect (CNHSE) in two Hatano--Nelson chains coupled locally at two bulk sites separated by an inclusive distance $d$. Whereas conventional CNHSE is commonly associated with weakly coupled subsystems, the critical behavior in our system persists in the strong inter-chain-coupling regime. Strong local hybridization generates high-energy impurity modes and effectively fragments the low-energy Hilbert space into geometry-selected sectors, one of which supports scale-free skin states. Independently, the count of states selected in the outer sector follows $2(L-d)$ for the two-chain system. These results establish local-coupling-induced fragmentation as a route to critical non-Hermitian behavior beyond the weak-coupling paradigm.

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Chong Wang, Linhu Li. 2026-09-06. Scale-Free Localization Morphing in Bilocally Coupled Hatano-Nelson Chains. https://arxiv.org/abs/2609.06799

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