中国物理B ›› 2007, Vol. 16 ›› Issue (4): 901-905.doi: 10.1088/1009-1963/16/4/005

• GENERAL • 上一篇    下一篇

Enhancing the capability of controlling quantum systems via ancillary systems

张明1, 高大远1, 谢红卫1, 胡德文1, 戴宏毅2   

  1. (1)College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha 410073, China; (2)College of Science, National University of Defense Technology, Changsha 410073, China
  • 收稿日期:2006-06-05 修回日期:2006-07-23 出版日期:2007-04-20 发布日期:2007-04-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No 60674040) and the National Natural Science Fund for Distinguished Young Scholars (Grant No 60225015).

Enhancing the capability of controlling quantum systems via ancillary systems

Zhang Ming(张明)a), Gao Da-Yuan(高大远)a), Dai Hong-Yi(戴宏毅)b), Xie Hong-Wei(谢红卫)a), and Hu De-Wen(胡德文)a)   

  1. a College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha 410073, China; b College of Science, National University of Defense Technology, Changsha 410073, China
  • Received:2006-06-05 Revised:2006-07-23 Online:2007-04-20 Published:2007-04-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No 60674040) and the National Natural Science Fund for Distinguished Young Scholars (Grant No 60225015).

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摘要： This paper explores the potential of controlling quantum systems by introducing ancillary systems and then performing unitary operation on the resulting composite systems. It generalizes the concept of pure state controllability for quantum systems and establishes the link between the operator controllability of the composite system and the generalized pure state controllability of its subsystem. It is constructively demonstrated that if a composite quantum system can be transferred between any pair of orthonormal pure vectors, then its subsystem is generalized pure-state controllable. Furthermore, the unitary operation and the coherent control can be concretely given to transfer the system from an initial state to the target state. Therefore, these properties may be potentially applied in quantum information, such as manipulating multiple quantum bits and creating entangled pure states. A concrete example has been given to illustrate that a maximally entangled pure state of a quantum system can be generated by introducing an ancillary system and performing open-loop coherent control on the resulting composite system.

Abstract: This paper explores the potential of controlling quantum systems by introducing ancillary systems and then performing unitary operation on the resulting composite systems. It generalizes the concept of pure state controllability for quantum systems and establishes the link between the operator controllability of the composite system and the generalized pure state controllability of its subsystem. It is constructively demonstrated that if a composite quantum system can be transferred between any pair of orthonormal pure vectors, then its subsystem is generalized pure-state controllable. Furthermore, the unitary operation and the coherent control can be concretely given to transfer the system from an initial state to the target state. Therefore, these properties may be potentially applied in quantum information, such as manipulating multiple quantum bits and creating entangled pure states. A concrete example has been given to illustrate that a maximally entangled pure state of a quantum system can be generated by introducing an ancillary system and performing open-loop coherent control on the resulting composite system.

Key words: quantum system, controllability, quantum computation, entanglement

中图分类号:  (Entanglement and quantum nonlocality)

  • 03.65.Ud
03.67.Lx (Quantum computation architectures and implementations)