Experimental investigation of decoherence in maximally entangled mixed states

Authors

  • Minaru Kawamura,

    Corresponding author
    1. Department of Electronic Engineering, Faculty of Engineering, Okayama University of Science, Ridai-cho 1-1, Okayama 700-0005, Japan
    • Department of Electronic Engineering, Faculty of Engineering, Okayama University of Science, Ridai-cho 1-1, Okayama 700-0005, Japan
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  • Takuji Morimoto,

    1. Undergraduate School of Engineering, Okayama University of Science, Ridai-cho 1-1, Okayama 700-0005, Japan
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  • Takashi Kumaya,

    1. Graduate School of Science, Okayama University of Science, Ridai-cho 1-1, Okayama 700-0005, Japan
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  • Ryuichi Sawae,

    1. Department of Applied Mathematics, Faculty of Science, Okayama University of Science, Ridai-cho 1-1, Okayama 700-0005, Japan
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  • Kenichi Takarabe,

    1. Department of Applied Science, Faculty of Science, Okayama University of Science, Ridai-cho 1-1, Okayama 700-0005, Japan
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  • Yoshinori Manmoto

    1. Department of Electronic Engineering, Faculty of Engineering, Okayama University of Science, Ridai-cho 1-1, Okayama 700-0005, Japan
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Abstract

Decoherence of the bipartite entangled mixed state in a five-qubit system has been studied experimentally with liquid-state nuclear magnetic resonance (NMR). The experimental results indicate that when only two qubits of the five qubits are partially initialized, the decoherence process of the bipartite entangled mixed state is not quantized, as the entanglability is weak. In contrast, when all five qubits are initialized, the decoherence process is quantized, which is understood to indicate that the entanglability is actually strong. From these results, it is conceivable that the entropy of the deviation density matrix is a crucial factor in measuring the entanglement in the liquid-state NMR quantum computer. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005

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