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Effects of Pure Dzyaloshinskii–Moriya Interaction with Magnetic Field on Entanglement in Intrinsic Decoherence |
| Da-Chuang Li1,2,3**, Xian-Ping Wang4**, Hu Li1,2, Xiao-Man Li1,2, Ming Yang2, Zhuo-Liang Cao1,2 |
1Institute for Quantum Control and Quantum Information and School of Electronic and Information Engineering, Hefei Normal University, Hefei 230601
2School of Physics and Material Science, Anhui University, Hefei 230039
3Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Modern Physics, University of Science and Technology of China, Hefei 230026
4Department of Physics, Fuyang Teachers College, Fuyang 236041
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| Cite this article: |
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Da-Chuang Li, Xian-Ping Wang, Hu Li et al 2016 Chin. Phys. Lett. 33 050301 |
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Abstract We investigate the effects of pure Dzyaloshinskii–Moriya (DM) interaction with magnetic field on entanglement in intrinsic decoherence, assuming that the system is initially in four Bell states $|\phi_{\pm}\rangle=(|00\rangle\pm|11\rangle)/\sqrt{2}$ and $|\psi_{\pm}\rangle=(|01\rangle\pm|10\rangle)/\sqrt{2}$, respectively. It is found that if the system is initially in the state $\rho_{1}(0)=|\phi_{+}\rangle\langle\phi_{+}|$, the entanglement can obtain its maximum when the DM interaction vector ${\boldsymbol D}$ is in the plane of $XOZ$ and magnetic field ${\boldsymbol B}={\boldsymbol B_{y}}$ with the infinite time $t$, moreover the entanglement is independent of $B_{y}$ and $t$ when ${\boldsymbol B_{y}}$ is perpendicular to ${\boldsymbol D}$. In addition, we obtain similar results when the system is initially in the states $\rho_{2}(0)=|\phi_{-}\rangle\langle\phi_{-}|$ or $\rho_{3}(0)=|\psi_{+}\rangle\langle\psi_{+}|$. However, we find that if the system is initially in the state $\rho_{4}(0)=|\psi_{-}\rangle\langle\psi_{-}|$, the entanglement can obtain its maximum for infinite $t$, when the DM vector is in the plane of $YOZ$, $XOZ$, or $XOY$, with the magnetic field parallel to $X$, $Y$, or $Z$ axis, respectively. Moreover, when the axial ${\boldsymbol B}$ is perpendicular to ${\boldsymbol D}$ for the initial state $\rho_{4}(0)$, the negativity oscillates with time $t$ and reaches a stable value, the larger the value of ${\boldsymbol B}$ is, the greater the stable value is, and the shorter the oscillation time of the negativity is. Thus we can adjust the direction and value of the external magnetic field to obtain the maximal entanglement, and avoid the adverse effects of external environment in some initial state. This is feasible within the current experimental technology.
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Received: 19 January 2016
Published: 31 May 2016
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| PACS: |
03.67.Mn
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(Entanglement measures, witnesses, and other characterizations)
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03.65.Yz
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(Decoherence; open systems; quantum statistical methods)
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75.10.Jm
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(Quantized spin models, including quantum spin frustration)
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