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Journal of Physics A Mathematical and Theoretical

Thermal entanglement of a three-qubit system in inhomogeneous magnetic fields

Z-N Hu, Kyung-Soo Yi, K.-S. Park

Published Jun 12, 2007• 11 citations
Publisher

Abstract

The quantum entanglement of the ground state and the thermal entanglement of the mixed thermal state of a three-qubit system with the Heisenberg interaction are investigated in detail in the presence of an inhomogeneous magnetic field. The concurrence of the model is compared with the magnetization, and the threshold temperature of the entanglement is discussed. The effects of the magnetic field and the coupling coefficient in the thermal entanglement are also examined by considering the concurrence of the three-qubit and two-qubit systems. We found that the thermal entanglement of the system exists at temperatures below the threshold temperature even if the ground state is unentangled.

DOI
10.1088/1751-8113/40/26/013

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The thermal entanglement in a two-qubit Heisenberg XXZXXZXXZ spin chain is investigated under an inhomogeneous magnetic field bbb. We show that the ground-state entanglement is independent of the interaction of zzz-component Jz{J}_{z}Jz​. The thermal entanglement at the fixed temperature can be enhanced when Jz{J}_{z}Jz​ increases. We strictly show that for any temperature TTT and Jz{J}_{z}Jz​, the entanglement is symmetric with respect to zero inhomogeneous magnetic field, and the critical inhomogeneous magnetic field bc{b}_{c}bc​ is independent of Jz{J}_{z}Jz​. The critical magnetic field Bc{B}_{c}Bc​ increases with the increasing $\ensuremath{\mid}b\ensuremath{\mid}$ but the maximum entanglement value that the system can arrive at becomes smaller.
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