中国物理B ›› 2024, Vol. 33 ›› Issue (6): 60308-060308.doi: 10.1088/1674-1056/ad2a70

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Exceptional points and quantum dynamics in a non-Hermitian two-qubit system

Yi-Xi Zhang(张益玺), Zhen-Tao Zhang(张振涛)†, Zhen-Shan Yang(杨震山)‡, Xiao-Zhi Wei(魏晓志), and Bao-Long Liang(梁宝龙)   

  1. School of Physics Science and Information Technology, Shandong Key Laboratory of Optical Communication Science and Technology, Liaocheng University, Liaocheng 252059, China
  • 收稿日期:2023-12-09 修回日期:2024-01-29 接受日期:2024-02-19 出版日期:2024-06-18 发布日期:2024-06-18
  • 通讯作者: Zhen-Tao Zhang, Zhen-Shan Yang E-mail:zhzhentao@163.com;yangzhenshan@lcu.edu.cn
  • 基金资助:
    This work is partly funded by the Natural Science Foundation of Shandong Province of China (Grant Nos. ZR2021MA091 and ZR2018MA044), Introduction and Cultivation Plan of Youth Innovation Talents for Universities of Shandong Province (Research and Innovation Team on Materials Modification and Optoelectronic Devices at extreme conditions).

Exceptional points and quantum dynamics in a non-Hermitian two-qubit system

Yi-Xi Zhang(张益玺), Zhen-Tao Zhang(张振涛)†, Zhen-Shan Yang(杨震山)‡, Xiao-Zhi Wei(魏晓志), and Bao-Long Liang(梁宝龙)   

  1. School of Physics Science and Information Technology, Shandong Key Laboratory of Optical Communication Science and Technology, Liaocheng University, Liaocheng 252059, China
  • Received:2023-12-09 Revised:2024-01-29 Accepted:2024-02-19 Online:2024-06-18 Published:2024-06-18
  • Contact: Zhen-Tao Zhang, Zhen-Shan Yang E-mail:zhzhentao@163.com;yangzhenshan@lcu.edu.cn
  • Supported by:
    This work is partly funded by the Natural Science Foundation of Shandong Province of China (Grant Nos. ZR2021MA091 and ZR2018MA044), Introduction and Cultivation Plan of Youth Innovation Talents for Universities of Shandong Province (Research and Innovation Team on Materials Modification and Optoelectronic Devices at extreme conditions).

摘要: We study the exceptional-point (EP) structure and the associated quantum dynamics in a system consisting of a non-Hermitian qubit and a Hermitian qubit. We find that the system possesses two sets of EPs, which divide the system-parameter space into $\mathcal{PT}$-symmetry unbroken, partially broken and fully broken regimes, each with distinct quantum-dynamics characteristics. Particularly, in the partially broken regime, while the $\mathcal{PT}$-symmetry is generally broken in the whole four-dimensional Hilbert space, it is preserved in a two-dimensional subspace such that the quantum dynamics in the subspace are similar to those in the $\mathcal{PT}$-symmetry unbroken regime. In addition, we reveal that the competition between the inter-qubit coupling and the intra-qubit driving gives rise to a complex pattern in the EP variation with system parameters.

关键词: non-Hermitian system, exceptional point, $\mathcal{PT}$-symmetry

Abstract: We study the exceptional-point (EP) structure and the associated quantum dynamics in a system consisting of a non-Hermitian qubit and a Hermitian qubit. We find that the system possesses two sets of EPs, which divide the system-parameter space into $\mathcal{PT}$-symmetry unbroken, partially broken and fully broken regimes, each with distinct quantum-dynamics characteristics. Particularly, in the partially broken regime, while the $\mathcal{PT}$-symmetry is generally broken in the whole four-dimensional Hilbert space, it is preserved in a two-dimensional subspace such that the quantum dynamics in the subspace are similar to those in the $\mathcal{PT}$-symmetry unbroken regime. In addition, we reveal that the competition between the inter-qubit coupling and the intra-qubit driving gives rise to a complex pattern in the EP variation with system parameters.

Key words: non-Hermitian system, exceptional point, $\mathcal{PT}$-symmetry

中图分类号:  (Quantum mechanics)

  • 03.65.-w
03.65.Yz (Decoherence; open systems; quantum statistical methods) 03.67.-a (Quantum information)