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arXiv · 2003.10099

Effective non-Hermitian physics for degenerate ground states of a nonHermitian Ising model with $\mathcal{RT}$ symmetry

Can Wang·Meng-Lei Yang·Cui-Xian Guo·Xiao-Ming Zhao·Su-Peng Kou
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Abstract

In this paper, based on a one-dimensional non-Hermitian spin model with $\mathcal{RT}$-invariant term, we study the non-Hermitian physics for the two (nearly) degenerate ground states. By using the high-order perturbation method, an effective pseudo-spin model is obtained to describe non-Hermitian physics for the two (nearly) degenerate ground states, which are precisely consistent with the numerical calculations. We found that there may exist effective (anti) $\mathcal{PT}$ symmetry for the effective pseudo-spin model of the two (nearly) degenerate ground states. In particular, there exists spontaneous (anti) $\mathcal{PT}$ -symmetry breaking for the topological degenerate ground states with tunable parameters in external fields. We also found that even a very tiny imaginary external field applied will drive $\mathcal{PT}$ phase transition.

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Can Wang, Meng-Lei Yang, Cui-Xian Guo, Xiao-Ming Zhao, Su-Peng Kou. 2020-03-23. Effective non-Hermitian physics for degenerate ground states of a nonHermitian Ising model with $\mathcal{RT}$ symmetry. https://doi.org/10.1209/0295-5075/128/41001

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