中国物理B ›› 2011, Vol. 20 ›› Issue (5): 50302-050302.doi: 10.1088/1674-1056/20/5/050302

• GENERAL • 上一篇    下一篇

Conservation issue of pairwise quantum discord and entanglement of two coupled qubits in a two-mode vacuum cavity

陈秋英, 方卯发, 肖兴, 周湘峰   

  1. Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control, Ministry of Education, and College of Physics and Information Science, Hunan Normal University, Changsha 410081, China
  • 收稿日期:2010-11-09 修回日期:2010-12-03 出版日期:2011-05-15 发布日期:2011-05-15
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 11074071), Hunan Provincial Natural Science Foundation, China (Grant Nos. 06JJ4003 and 06JJ2014), and the Young Science Research Foundation of Hunan Provincial Education Depa

Conservation issue of pairwise quantum discord and entanglement of two coupled qubits in a two-mode vacuum cavity

Chen Qiu-Ying (陈秋英), Fang Mao-Fa (方卯发), Xiao Xing (肖兴), Zhou Xiang-Feng (周湘峰)   

  1. Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control, Ministry of Education, and College of Physics and Information Science, Hunan Normal University, Changsha 410081, China
  • Received:2010-11-09 Revised:2010-12-03 Online:2011-05-15 Published:2011-05-15
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 11074071), Hunan Provincial Natural Science Foundation, China (Grant Nos. 06JJ4003 and 06JJ2014), and the Young Science Research Foundation of Hunan Provincial Education Department, China (Grant No. 04B070).

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摘要： The conservation issues of pairwise quantum discord and entanglement of two qubits coupled to a two-mode vacuum cavity are investigated by considering the dipole–dipole interaction between two qubits. It is found that the sum of the square of the pairwise quantum discords and the sum of the square of the pairwise concurrences are both conserved in the strong dipole–dipole interaction limit. However, in the middle dipole–dipole and weak dipole–dipole interaction limits, the sum of the square of the pairwise concurrences is still conserved while the sum of the square of the pairwise discords is not. The crucial reason for this is that the quantum discords are not equivalent if the measurements are performed on different subsystems in a general situation. So it is very important for quantum computation depending on the quantum discord to select the target performed by the measurements.

Abstract: The conservation issues of pairwise quantum discord and entanglement of two qubits coupled to a two-mode vacuum cavity are investigated by considering the dipole–dipole interaction between two qubits. It is found that the sum of the square of the pairwise quantum discords and the sum of the square of the pairwise concurrences are both conserved in the strong dipole–dipole interaction limit. However, in the middle dipole–dipole and weak dipole–dipole interaction limits, the sum of the square of the pairwise concurrences is still conserved while the sum of the square of the pairwise discords is not. The crucial reason for this is that the quantum discords are not equivalent if the measurements are performed on different subsystems in a general situation. So it is very important for quantum computation depending on the quantum discord to select the target performed by the measurements.

Key words: quantum discord, quantum entanglement, dipole–dipole (DD) interaction

中图分类号:  (Foundations of quantum mechanics; measurement theory)

  • 03.65.Ta
03.67.Mn (Entanglement measures, witnesses, and other characterizations) 42.50.Dv (Quantum state engineering and measurements)