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 and Critical Behavior of Magnetic Properties on a Triangulated Kagomé Lattice

10.14311/1344 ◽  
2011 ◽  
Vol 51 (2) ◽  
Author(s):  
N. Ananikian ◽  
L. Ananikyan ◽  
L. Chakhmakhchyan ◽  
A. Kocharian
Keyword(s):  
Magnetic Field ◽  
Heisenberg Model ◽  
Quantum Phase Transitions ◽  
Exchange Interactions ◽  
Effective Field ◽  
Threshold Temperature ◽  
Kagome Lattice ◽  
Thermal Entanglement ◽  
Kagomé Lattice ◽  
Bogoliubov Inequality

The equilibrium magnetic and entanglement properties in a spin-1/2 Ising-Heisenberg model on a triangulated Kagomé lattice are analyzed by means of the effective field for the Gibbs-Bogoliubov inequality. The calculation is reduced to decoupled individual (clusters) trimers due to the separable character of the Ising-type exchange interactions between the Heisenberg trimers. The concurrence in terms of the three qubit isotropic Heisenberg model in the effective Ising field in the absence of a magnetic field is non-zero. The magnetic and entanglement properties exhibit common (plateau, peak) features driven by a magnetic field and (antiferromagnetic) exchange interaction. The (quantum) entangled and non-entangled phases can be exploited as a useful tool for signalling the quantum phase transitions and crossovers at finite temperatures. The critical temperature of order-disorder coincides with the threshold temperature of thermal entanglement.

Phase Transition in 2D Anisotropic Ising Model with Next-Nearest Neighbor Interactions in a Magnetic Field

SPIN ◽  
2018 ◽  
Vol 08 (03) ◽  
pp. 1850010
Author(s):  
D. Farsal ◽  
M. Badia ◽  
M. Bennai
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Phase Diagram ◽  
Monte Carlo ◽  
Magnetic Susceptibility ◽  
Critical Temperature ◽  
Ising Model ◽  
Nearest Neighbor ◽  
Two Dimensional ◽  
The Magnetic Field

The critical behavior at the phase transition of the ferromagnetic two-dimensional anisotropic Ising model with next-nearest neighbor (NNN) couplings in the presence of the field is determined using mainly Monte Carlo (MC) method. This method is used to investigate the phase diagram of the model and to verify the existence of a divergence at null temperature which often appears in two-dimensional systems. We analyze also the influence of the report of the NNN interactions [Formula: see text] and the magnetic field [Formula: see text] on the critical temperature of the system, and we show that the critical temperature depends on the magnetic field for positive values of the interaction. Finally, we have investigated other thermodynamical qualities such as the magnetic susceptibility [Formula: see text]. It has been shown that their thermal behavior depends qualitatively and quantitatively on the strength of NNN interactions and the magnetic field.

PAIRWISE ENTANGLEMENT IN THE N-QUBIT XX MODEL WITH DZYALOSHINSKI–MORIYA INTERACTION AND MAGNETIC FIELD

2011 ◽  
Vol 25 (16) ◽  
pp. 2135-2148
Author(s):  
BIN ZHOU
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
Magnetic Fields ◽  
Nearest Neighbor ◽  
Zero Temperature ◽  
Thermal Entanglement ◽  
Dm Interaction ◽  
Xx Model ◽  
Moriya Interaction

In this paper, we investigate the role of Dzyaloshinski–Moriya (DM) interaction in the pairwise entanglement in the three- and four-qubit XX models with magnetic field. In the four-qubit model, the pairwise entanglements of two nearest-neighbor qubits and two next-neighbor qubits are investigated, respectively. The dependences of the critical temperature at which the pairwise thermal entanglement disappears on DM interaction and magnetic fields are studied in details. At zero temperature, the entanglement can undergo sudden changes with adjustment of the parameters, and the general results of the concurrence are obtained in all cases.

THERMAL ENTANGLEMENT IN SPIN SYSTEMS

2006 ◽  
Vol 20 (30n31) ◽  
pp. 5117-5121 ◽  
Author(s):  
N. CANOSA ◽  
R. ROSSIGNOLI
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
Applied Magnetic Field ◽  
Uniform Magnetic Field ◽  
Mean Field ◽  
Spin Systems ◽  
Thermal Entanglement ◽  
Global Entanglement ◽  
Thermal States

We examine the entanglement of thermal states of n spins interacting through an XYZ type Heisenberg coupling in the presence of a uniform magnetic field, by evaluating the negativities of bipartite partitions of the whole system and subsystems. The corresponding limit temperatures for entanglement are also examined. Results indicate that limit temperatures for global entanglement depend on the type of partition and are higher than those limiting pairwise entanglement, and that their behavior with anisotropy and applied magnetic field may differ significantly from that of the corresponding mean field critical temperature.

scholarly journals INFLUENCE OF ANISOTROPY AND MAGNETIC FIELD ON THERMAL ENTANGLEMENT IN HEISENBERG MODEL AND THERMODYNAMIC ANALYSIS OF MODEL

2017 ◽  
Vol 8 (2) ◽  
Author(s):  
Мilan Pantić ◽  
Nemanja Micić ◽  
Milica Pavkov Hrvojević ◽  
Slobodan Radošević ◽  
Petar Mali
Keyword(s):  
Magnetic Field ◽  
Thermodynamic Properties ◽  
Strong Magnetic Field ◽  
Thermodynamic Analysis ◽  
Interaction Parameter ◽  
Heisenberg Model ◽  
Thermal Entanglement ◽  
Dm Interaction ◽  
Analytical Expressions

The thermal entanglement in a two-qubit anisotropic Heisenberg XXZ system, also XYZ system, with Dzyaloshinskii-Moriya (DM) couplings in an inhomogenous magnetic field, was studied. The effects of these two kinds of anisotropies on the thermal entanglement have been studied in detail in the concept for concurrence, the measure of entanglement. The analytical expressions of concurrence are obtained for this model. It is found that the DM interaction can enhance thermal entanglement and can be efficiently controlled by the DM interaction parameter and ehchange interaction Jx, Jy and Jz. When D is large enough, the entanglement can exist for larger temperatures and strong magnetic field. We also analysed thermodynamic properties of Heisenberg model and the most important results were shown in the paper.

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