中国物理B ›› 2006, Vol. 15 ›› Issue (4): 681-686.doi: 10.1088/1009-1963/15/4/005

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Quantum entanglement and quantum nonlocality for N-photon entangled states

匡乐满1, 孙艳华2   

  1. (1)Department of Physics, Hunan Normal University,Changsha 410081, China; (2)Department of Physics, Hunan Normal University,Changsha 410081, China;Haikou College of Economic and Vocational Technology, Haikou 570203, China
  • 收稿日期:2005-08-15 修回日期:2005-09-09 出版日期:2006-04-20 发布日期:2006-04-20
  • 基金资助:
    Project supported by the National Fundamental Research Program (Grant No 2001CB309310), the National Natural Science Foundation of China (Grant Nos 10325523, 90203018 and 10075018), the Foundation of the Ministry of Education of China,and the Educational Committee of Hunan Province (Grant Nos 200248 and 02A026).

Quantum entanglement and quantum nonlocality for N-photon entangled states

Sun Yan-Hua (孙艳华)ab, Kuang Le-Man (匡乐满)a   

  1. a Department of Physics, Hunan Normal University,Changsha 410081, China; b Haikou College of Economic and Vocational Technology, Haikou 570203, China
  • Received:2005-08-15 Revised:2005-09-09 Online:2006-04-20 Published:2006-04-20
  • Supported by:
    Project supported by the National Fundamental Research Program (Grant No 2001CB309310), the National Natural Science Foundation of China (Grant Nos 10325523, 90203018 and 10075018), the Foundation of the Ministry of Education of China,and the Educational Committee of Hunan Province (Grant Nos 200248 and 02A026).

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摘要： Quantum entanglement and quantum nonlocality of N-photon entangled states |\psiN m\rangle =Cm[\cos\gamma|N-m\rangle1|m\rangle2 +\e{\i\θm}\sin\gamma|m\rangle1|N-m\rangle2] and their superpositions are studied. We point out that the relative phase θm affects the quantum nonlocality but not the quantum entanglement for the state |\psiN m\rangle. We show that quantum nonlocality can be controlled and manipulated by adjusting the state parameters of |\psiN m\rangle, superposition coefficients, and the azimuthal angles of the Bell operator. We also show that the violation of the Bell inequality can reach its maximal value under certain conditions. It is found that quantum superpositions based on |\psiN m\rangle can increase the amount of entanglement, and give more ways to reach the maximal violation of the Bell inequality.

关键词: quantum entanglement, quantum nonlocality, Bell inequality

Abstract: Quantum entanglement and quantum nonlocality of N-photon entangled states $|\psi_{Nm}\rangle=C_m[\cos\gamma|N-m\rangle_1|m\rangle_2+{\rm e}^{{\rm i}\theta_m}\sin\gamma|m\rangle_1|N-m\rangle_2]$ and their superpositions are studied. We point out that the relative phase $\theta_m$ affects the quantum nonlocality but not the quantum entanglement for the state $|\psi_{Nm}\rangle$. We show that quantum nonlocality can be controlled and manipulated by adjusting the state parameters of $|\psi_{Nm}\rangle$, superposition coefficients, and the azimuthal angles of the Bell operator. We also show that the violation of the Bell inequality can reach its maximal value under certain conditions. It is found that quantum superpositions based on $|\psi_{Nm}\rangle$ can increase the amount of entanglement, and give more ways to reach the maximal violation of the Bell inequality.

Key words: quantum entanglement, quantum nonlocality, Bell inequality

中图分类号:  (Entanglement and quantum nonlocality)

  • 03.65.Ud
42.50.Dv (Quantum state engineering and measurements)