Correlations at higher-order exceptional points in non-Hermitian models

• URL: http://arxiv.org/abs/2304.10280v2
• Date: Tue, 15 Aug 2023 17:44:18 GMT
• Title: Correlations at higher-order exceptional points in non-Hermitian models
• Authors: Doru Sticlet, C\u{a}t\u{a}lin Pa\c{s}cu Moca, Bal\'azs D\'ora
• Abstract summary: We investigate the decay of spatial correlations of $mathcalPT$-symmetric non-Hermitian one-dimensional models that host higher-order exceptional points. Beyond a certain correlation length, they develop anomalous power-law behavior. The correlation length is also reflected in the entanglement entropy where it marks a change from logarithmic growth at short distance to a constant value at large distance.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We investigate the decay of spatial correlations of $\mathcal{PT}$-symmetric non-Hermitian one-dimensional models that host higher-order exceptional points. Beyond a certain correlation length, they develop anomalous power-law behavior that indicates strong suppression of correlations in the non-Hermitian setups as compared to the Hermitian ones. The correlation length is also reflected in the entanglement entropy where it marks a change from logarithmic growth at short distance to a constant value at large distance, characteristic of an insulator, despite the spectrum being gapless. Two different families of models are investigated, both having a similar spectrum constrained by particle-hole symmetry. The first model offers an experimentally attractive way to generate arbitrary higher-order exceptional points and represents a non-Hermitian extension of the Dirac Hamiltonian for general spin. At the critical point it displays a decay of the correlations $\sim 1/x^2$ and $1/x^3$ irrespective of the order of the exceptional point. The second model is constructed using unidirectional hopping and displays enhanced suppression of correlations $\sim 1/x^a$, $a\ge 2$ with a power law that depends on the order of the exceptional point.

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