Quantum Fisher Information and the Heisenberg Limit in Superpositions of Two W States and Symmetric State

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• 作者：Xiao-Fang Ouyang (1) oyxf328@126.com
  Run-Sheng Wu (1)
• 关键词：Quantum Fisher information &#8211 ; Superposition &#8211 ; Heisenberg limit
• 刊名：International Journal of Theoretical Physics
• 出版年：2012
• 出版时间：November 2012
• 年：2012
• 卷：51
• 期：11
• 页码：3345-3349
• 全文大小：433.5 KB
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• 作者单位：1. Department of New Energy Science and Engineering, Xinyu College, Xinyu, 338004 P.R. China
• ISSN：1572-9575

文摘

We investigate the quantum Fisher information and the Heisenberg limit in superposition of a four-qubit symmetric state and two W states. Numerical and analytical calculations for quantum Fisher information and the Heisenberg limit of the four-qubit state are driven. It is shown that quantum Fisher information of the four-qubit state depends on the superposition coefficients and the relative phase. It is also shown that under certain conditions, the maximal quantum Fisher information occurred; which leads to the estimation sensitivity beats the Heisenberg limit.