中国物理B ›› 2009, Vol. 18 ›› Issue (7): 2642-2648.doi: 10.1088/1674-1056/18/7/004

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Application of quantum algorithms to direct measurement of concurrence of a two-qubit pure state

王洪福1, 张寿2   

  1. (1)Center for the Condensed-Matter Science and Technology, Harbin Institute of Technology, Harbin 150001, China; (2)Center for the Condensed-Matter Science and Technology, Harbin Institute of Technology, Harbin 150001, China;Department of Physics, College of Science, Yanbian University, Yanji 133002, China
  • 收稿日期:2008-10-13 修回日期:2008-11-05 出版日期:2009-07-20 发布日期:2009-07-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No 60667001).

Application of quantum algorithms to direct measurement of concurrence of a two-qubit pure state

Wang Hong-Fu(王洪福)a) and Zhang Shou(张寿)a)b)†   

  1. a Center for the Condensed-Matter Science and Technology, Harbin Institute of Technology, Harbin 150001, China; b Department of Physics, College of Science, Yanbian University, Yanji 133002, China
  • Received:2008-10-13 Revised:2008-11-05 Online:2009-07-20 Published:2009-07-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No 60667001).

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摘要： This paper proposes a method to measure directly the concurrence of an arbitrary two-qubit pure state based on a generalized Grover quantum iteration algorithm and a phase estimation algorithm. The concurrence can be calculated by applying quantum algorithms to two available copies of the bipartite system, and a final measurement on the auxiliary working qubits gives a better estimation of the concurrence. This method opens new prospects of entanglement measure by the application of quantum algorithms. The implementation of the protocol would be an important step toward quantum information processing and more complex entanglement measure of the finite-dimensional quantum system with an arbitrary number of qubits.

Abstract: This paper proposes a method to measure directly the concurrence of an arbitrary two-qubit pure state based on a generalized Grover quantum iteration algorithm and a phase estimation algorithm. The concurrence can be calculated by applying quantum algorithms to two available copies of the bipartite system, and a final measurement on the auxiliary working qubits gives a better estimation of the concurrence. This method opens new prospects of entanglement measure by the application of quantum algorithms. The implementation of the protocol would be an important step toward quantum information processing and more complex entanglement measure of the finite-dimensional quantum system with an arbitrary number of qubits.

Key words: concurrence, quantum algorithm, entanglement measure

中图分类号:  (Quantum computation architectures and implementations)

  • 03.67.Lx
03.65.Ta (Foundations of quantum mechanics; measurement theory) 03.65.Ud (Entanglement and quantum nonlocality) 03.67.Mn (Entanglement measures, witnesses, and other characterizations)