THERMAL AND NON-UNIFORM MAGNETIC QUANTUM DISCORD IN THE TWO-QUBIT HEISENBERG XXZ MODEL

2012 ◽  
Vol 26 (05) ◽  
pp. 1150028 ◽  
Author(s):  
RUI-HUA XIAO ◽  
ZHAN-YING GUO ◽  
JIAN-XING FANG
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
Uniform Magnetic Field ◽  
Quantum Discord ◽  
Critical Magnetic Field ◽  
Thermal Entanglement ◽  
Xxz Model ◽  
Analytical Expressions ◽  
Heisenberg Xxz Model

The thermal quantum discord (QD) is investigated in the two-qubit anisotropic Heisenberg XXZ model under an external non-uniform magnetic field along the Z-axis. We obtain the analytical expressions of the thermal QD and thermal entanglement measured by concurrence (C). It shows that for any temperature T, QD gradually decreases with the increase of non-uniform magnetic field |b|, in some regions where C increases while QD decreases. It is also found that thermal quantum discord does not vanish at finite temperatures, but concurrence vanishes completely at a critical temperature. It is shown that for a higher value of JZ, the system has a stronger QD. There is a critical magnetic field B c , which increases with the increasing b. QD decay monotonically (for B < B c ) when temperature T increases, or initially increases to some peaks and then decrease (for B > B c ).

Thermal entanglement in a mixed-spin Heisenberg XXZ model under a nonuniform external magnetic field

2009 ◽  
Vol 52 (12) ◽  
pp. 1919-1924 ◽  
Author(s):  
Fei Wang ◽  
HongHui Jia ◽  
HaiLiang Zhang ◽  
XueAo Zhang ◽  
ShengLi Chang
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Thermal Entanglement ◽  
Xxz Model ◽  
Mixed Spin ◽  
Heisenberg Xxz Model

THREE-QUBITS GROUND STATE AND THERMAL ENTANGLEMENT OF ANISOTROPIC HEISENBERG (XXZ) AND ISING MODELS WITH DZYALOSHINSKII-MORIYA INTERACTION

2011 ◽  
Vol 09 (04) ◽  
pp. 1057-1079 ◽  
Author(s):  
R. JAFARI ◽  
A. LANGARI
Keyword(s):  
Magnetic Field ◽  
Ground State ◽  
Ising Models ◽  
Zero Temperature ◽  
Thermal Entanglement ◽  
Xxz Model ◽  
Dm Interaction ◽  
Remarkable Result ◽  
Moriya Interaction ◽  
Heisenberg Xxz Model

We have studied the symmetric and non-symmetric pairwise ground state and thermal entanglement in three-qubits system. We have considered the anisotropic Heisenberg (XXZ) model in the presence of Dzyaloshinskii–Moriya (DM) interaction in addition to the Ising model in a magnetic field with DM interaction. We have found that the increment of DM interaction and magnetic field can enhance and reduce the entanglement of the system. We have shown that the non-symmetric pairwise state has higher value concurrence and critical temperature (above which the entanglement vanishes) than the symmetric pairwise one. For the negative anisotropy, the non-symmetric entanglement is a monotonic function of DM interaction while for positive anisotropy, it has a maximum versus DM parameter and vanishes for larger values of DM interaction. The conditions for the existence of thermal entanglement are discussed in detail. The most remarkable result appears at zero temperature where the three-qubits ground state entanglement of the system (in spite of two-qubits counterpart) shows the fingerprint of the quantum phase transition for a system of infinite number of qubits.

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.

THERMAL ENTANGLEMENT IN THE TWO-QUBIT SYSTEMS CONSTRUCTED FROM THE YANG-BAXTER $\check{R}$-MATRIX

2009 ◽  
Vol 07 (05) ◽  
pp. 879-889 ◽  
Author(s):  
CHUNFANG SUN ◽  
TAOTAO HU ◽  
GANGCHENG WANG ◽  
CHUNFENG WU ◽  
KANG XUE
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
Critical Magnetic Field ◽  
Spin Interaction ◽  
Thermal Entanglement ◽  
R Matrix

Some new Hamiltonians are constructed via the unitary Yang-Baxter matrices [Formula: see text] acting on a Hamiltonian H0 which describes nearest spin-spin interaction. By the concept of concurrence, we explore the thermal entanglement of these systems. We find that the interaction of z-component of two neighboring spins g has great influences on the thermal entanglement. It not only influences the critical temperature Tc, but can also influence the critical magnetic field Bc.

THERMAL ENTANGLEMENT IN THE ANISOTROPIC XXZ MODEL UNDER AN INHOMOGENEOUS MAGNETIC FIELD

2006 ◽  
Vol 20 (15) ◽  
pp. 2117-2127 ◽  
Author(s):  
KE-DONG WU ◽  
BIN ZHOU
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
Inhomogeneous Magnetic Field ◽  
Thermal Entanglement ◽  
Anisotropic Parameter ◽  
Xxz Model

We investigate the thermal entanglement in the two-qubit anisotropic XXZ model in the presence of an external inhomogeneous magnetic field along the z axis. Concurrence, the measurement of entanglement is calculated. The effects of the anisotropic parameter Δ on the thermal entanglement are studied carefully for both the antiferromagnetic and ferromagnetic cases. The critical temperature Tc can also be controlled by the anisotropic parameter Δ.

Influence of magnetic field on swap operation in Heisenberg XXZ model

2009 ◽  
Vol 404 (8-11) ◽  
pp. 1116-1118 ◽  
Author(s):  
Jia Liu ◽  
Guo-Feng Zhang ◽  
Zi-Yu Chen
Keyword(s):  
Magnetic Field ◽  
Xxz Model ◽  
Swap Operation ◽  
Heisenberg Xxz Model

scholarly journals Meissner effect in holographic superconductors with Dirac–Born–Infeld electrodynamics

2019 ◽  
Vol 35 (06) ◽  
pp. 2050020
Author(s):  
Debabrata Ghorai ◽  
Sunandan Gangopadhyay ◽  
Rabin Banerjee
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
Meissner Effect ◽  
Critical Magnetic Field ◽  
Matching Method ◽  
Holographic Superconductors

In this paper, we have investigated the Meissner effect of holographic superconductors in the presence of Dirac–Born–Infeld electrodynamics. The matching method is applied to obtain the critical magnetic field and the critical temperature. The critical magnetic field obtained from this investigation shows the effects of the DBI parameter [Formula: see text] and differs from that obtained from Born electrodynamics because of the extra [Formula: see text] term in the Dirac–Born–Infeld theory. It is observed that the critical magnetic field increases in Dirac–Born–Infeld theory compared to that in the Born theory.

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