| Issue |
EPL
Volume 128, Number 4, November 2019
|
|
|---|---|---|
| Article Number | 41001 | |
| Number of page(s) | 6 | |
| Section | The Physics of Elementary Particles and Fields | |
| DOI | https://doi.org/10.1209/0295-5075/128/41001 | |
| Published online | 20 January 2020 | |
Effective non-Hermitian physics for degenerate ground states of a non-Hermitian Ising model with 
symmetry
1 Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University - Beijing 100875, China
2 Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences Beijing 100190, China
(a) spkou@bnu.edu.cn (corresponding author)
Received: 2 September 2019
Accepted: 21 November 2019
In this paper, based on a one-dimensional non-Hermitian spin model with -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) 
symmetry for the effective pseudo-spin model of the two (nearly) degenerate ground states. In particular, there exists spontaneous (anti) -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 phase transition.
PACS: 11.30.Er – Charge conjugation, parity, time reversal, and other discrete symmetries / 75.10.Jm – Quantized spin models, including quantum spin frustration / 64.70.Tg – Quantum phase transitions
© EPLA, 2020
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