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Maximizing Thermal Entanglement of XY Model Using Site-Dependent Magnetic Fields in Specific Directions |
| CHAN Wen-Ling1;YANG Dong2;GU Shi-Jian1 |
| 1Department of Physics and ITP, The Chinese University of Hong Kong, Hong Kong2Laboratory for Quantum Information and Department of Physics, China Jiliang University, Hangzhou 310018 |
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| Cite this article: |
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CHAN Wen-Ling, YANG Dong, GU Shi-Jian 2008 Chin. Phys. Lett. 25 832-835 |
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Abstract We study the thermal entanglement by means of concurrence in a two-qubit isotropic XY model in the presence of site-dependent external magnetic fields in arbitrary directions. We find that at a given temperature and magnetic field
strength, the mirror symmetry of the two fields about the x--y plane is a necessary condition for maximum entanglement. However, if there is no constraint on the field strengths, then the necessary condition for maximum entanglement reduces to the configuration that the two fields are vertical, anti-parallel and with the same strength. We also investigate the anisotropic XY model and find that the above conclusion more or less holds.
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| Keywords:
03.67.Lx
03.67.Mn
75.10.Jm
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Received: 06 December 2007
Published: 27 February 2008
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| PACS: |
03.67.Lx
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(Quantum computation architectures and implementations)
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03.67.Mn
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(Entanglement measures, witnesses, and other characterizations)
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75.10.Jm
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(Quantized spin models, including quantum spin frustration)
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