Thermal Entanglement of a Three-Qubit Heisenberg Chain with a Nonuniform Magnetic Field

2008 ◽  
Vol 49 (6) ◽  
pp. 1635-1638 ◽  
Author(s):  
Yang Guo-Hui ◽  
Zhou Ling
Keyword(s):  
Magnetic Field ◽  
Nonuniform Magnetic Field ◽  
Heisenberg Chain ◽  
Thermal Entanglement

ENTANGLEMENT IN THE XY HEISENBERG MODEL

2004 ◽  
Vol 18 (19n20) ◽  
pp. 1059-1065 ◽  
Author(s):  
XIN TIAN ◽  
JIA-TIH LIN ◽  
LIANG LIU ◽  
DE-LONG REN
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
Ising Model ◽  
Heisenberg Model ◽  
Nonuniform Magnetic Field ◽  
Xy Model ◽  
Thermal Entanglement ◽  
Isotropic Model

We investigate the thermal entanglement of two-qubit anisotropic Heisenberg XY model in the presence of an external nonuniform magnetic field B along the z-axis. Concurrence, the measure of entanglement is calculated and its property is studied in different cases. Two best models, Ising model under a uniform magnetic and isotropic model in a nonuniform magnetic field, are discovered. In the two models, the critical temperature Tc (above which there is no entanglement) can be enhanced and its concurrence is maximal.

scholarly journals THERMAL ENTANGLEMENT IN THE TWO-QUBIT HEISENBERG XYZ MODEL

2004 ◽  
Vol 02 (03) ◽  
pp. 393-405 ◽  
Author(s):  
GUSTAVO RIGOLIN
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Thermal Equilibrium ◽  
Coupling Constants ◽  
Heisenberg Chain ◽  
Thermal Entanglement ◽  
One Dimensional ◽  
Analytical Expression ◽  
Monotonically Decreasing Function

We study the entanglement of a two-qubit one-dimensional XYZ Heisenberg chain in thermal equilibrium at temperature T. We obtain an analytical expression for the concurrence of this system in terms of the parameters of the Hamiltonian and T. We show that depending on the relation among the coupling constants, it is possible to increase the amount of entanglement of the system by increasing its anisotropy. We also show numerically that for all sets of the coupling constants entanglement is a monotonically decreasing function of the temperature T, proving that we must have at least an external magnetic field in the z-direction to obtain a behavior where entanglement increases with T.

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