Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:quant-ph/0501029 · Physical Review A

Thermal entanglement between alternate qubits of a four-qubit Heisenberg XX chain in a magnetic field

Min Cao, Shiqun Zhu

Published Mar 24, 2005• 61 citations
arXivHTMLPDF

Abstract

The concurrence of two alternate qubits in a four-qubit Heisenberg $XX$ chain is investigated when a uniform magnetic field $B$ is included. It is found that there is no thermal entanglement between alternate qubits if $B$ is close to zero. A magnetic field can induce entanglement in a certain range both for the antiferromagnetic and ferromagnetic cases. Near zero temperature, the entanglement undergoes two sudden changes with increasing value of the magnetic field $B$. This is due to the changes in the ground state. This novel property may be used as a quantum entanglement switch. The anisotropy in the system can also induce the entanglement between two alternate qubits.

DOI
10.1103/physreva.71.034311

Related papers

Pairwise Entanglement in the Four-qubit Heisenberg XX Open Chain

Wanqiang Cao

The pairwise entanglement in the four-qubit Heisenberg XX open chain with external magnetic fields is calculated,and the analytical expressions for the measures of entanglement Concurrence are obtained.It is found that the entanglement between the boundary qubits can reach the value of 0.28 in the system with uniform external magnetic fields.In addition,in the Heisenberg XX model with external magnetic fields on the two boundary qubits,the two non-boundary qubits will be in the maximal entanglement by increasing the magnetic field at low temperature.

Journal of Yanbian University•Jan 1, 2009•0 citations

Thermal entanglement in three-qubit Heisenberg models

Wang, X, Fu, H, A. I. Solomon

We study pairwise thermal entanglement in three-qubit Heisenberg models and obtain analytic expressions for the concurrence. We find that thermal entanglement is absent from both the antiferromagnetic XXZ model, and the ferromagnetic XXZ model with anisotropy parameter Δ≥1. Conditions for the existence of thermal entanglement are discussed in detail, as is the role of degeneracy and the effects of magnetic fields on thermal entanglement and the quantum phase transition. Specifically, we find that the uniform magnetic field can induce entanglement in the antiferromagnetic XXX model, but cannot induce entanglement in the ferromagnetic XXX model.

•May 16, 2001•108 citations

Thermal entanglement in three-qubit Heisenberg models

Xiaoguang Wang, Hongchen Fu, A. I. Solomon

We study pairwise thermal entanglement in three-qubit Heisenberg models and obtain analytic expressions for the concurrence. We find that thermal entanglement is absent from both the antiferromagnetic XXZ model, and the ferromagnetic XXZ model with anisotropy parameter Δ⩾1. Conditions for the existence of thermal entanglement are discussed in detail, as is the role of degeneracy and the effects of magnetic fields on thermal entanglement and the quantum phase transition. Specifically, we find that the uniform magnetic field can induce entanglement in the antiferromagnetic XXX model, but cannot induce entanglement in the ferromagnetic XXX model.

arXiv:quant-ph/0105075•Journal of Physics A Mathematical and General•Dec 19, 2001•144 citations

Effects of Anisotropy on Pair-wise Entanglement of a Four-Qubit Heisenberg XXZ Chain

Cao Min, Zhu Shi-Qun

The pair-wise thermal entanglement in a four-qubit Heisenberg XXZ chain is investigated to study the role of anisotropy when an external magnetic field is included. It is found that pair-wise entanglement is absent between nearest- and next-nearest neighbouring qubits with anisotropic parameter Δ⩽−1. For two nearest-neighbouring qubits, increasing the parameter can not only induce the entanglement, but also extend the entanglement region in terms of magnetic field B and temperature T . For two next-nearest-neighbouring qubits, increasing anisotropic parameter can shift the location of the entanglement and control the extent of the entanglement in terms of magnetic field at a finite temperature.

Chinese Physics Letters•Oct 26, 2006•6 citations

Thermal Entanglement of a Two-Qubit Heisenberg XYZ Chain

Min Cao

Thermal entanglement of a two-qubit Heisenberg XYZ chain is studied.It is found that the ground state entanglement maintains a maximal constant until it drops suddenly at a critical magnetic field.Increasing the value of can extend the entanglement region in terms of temperature and magnetic field.At a finite temperature,increasing the anisotropy parameter can enhance and extend the revival entanglement when the magnetic field is beyond the critical point.These results may provide theoretical proof for manipulating the entanglement with magnetic field,strength of interaction and anisotropy parameter.

Journal of Nantong University•Jan 1, 2008•0 citations

Thermal entanglement in a two-qubit Heisenberg XXZ spin chain under an inhomogeneous magnetic field

Guo‐Feng Zhang, Shu‐Shen Li

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

arXiv:quant-ph/0509009•Physical Review A•Sep 2, 2005•227 citations
The concurrence of two alternate qubits in a four-qubit Heisenberg XXXXXX chain is investigated when a uniform magnetic field BBB is included. It is found that there is no thermal entanglement between alternate qubits if BBB is close to zero. A magnetic field can induce entanglement in a certain range both for the antiferromagnetic and ferromagnetic cases. Near zero temperature, the entanglement undergoes two sudden changes with increasing value of the magnetic field BBB. This is due to the changes in the ground state. This novel property may be used as a quantum entanglement switch. The anisotropy in the system can also induce the entanglement between two alternate qubits.
The pairwise entanglement in the four-qubit Heisenberg XX open chain with external magnetic fields is calculated,and the analytical expressions for the measures of entanglement Concurrence are obtained.It is found that the entanglement between the boundary qubits can reach the value of 0.28 in the system with uniform external magnetic fields.In addition,in the Heisenberg XX model with external magnetic fields on the two boundary qubits,the two non-boundary qubits will be in the maximal entanglement by increasing the magnetic field at low temperature.
We study pairwise thermal entanglement in three-qubit Heisenberg models and obtain analytic expressions for the concurrence. We find that thermal entanglement is absent from both the antiferromagnetic XXZ model, and the ferromagnetic XXZ model with anisotropy parameter Δ≥1. Conditions for the existence of thermal entanglement are discussed in detail, as is the role of degeneracy and the effects of magnetic fields on thermal entanglement and the quantum phase transition. Specifically, we find that the uniform magnetic field can induce entanglement in the antiferromagnetic XXX model, but cannot induce entanglement in the ferromagnetic XXX model.
We study pairwise thermal entanglement in three-qubit Heisenberg models and obtain analytic expressions for the concurrence. We find that thermal entanglement is absent from both the antiferromagnetic XXZ model, and the ferromagnetic XXZ model with anisotropy parameter Δ⩾1. Conditions for the existence of thermal entanglement are discussed in detail, as is the role of degeneracy and the effects of magnetic fields on thermal entanglement and the quantum phase transition. Specifically, we find that the uniform magnetic field can induce entanglement in the antiferromagnetic XXX model, but cannot induce entanglement in the ferromagnetic XXX model.
The pair-wise thermal entanglement in a four-qubit Heisenberg XXZ chain is investigated to study the role of anisotropy when an external magnetic field is included. It is found that pair-wise entanglement is absent between nearest- and next-nearest neighbouring qubits with anisotropic parameter Δ⩽−1. For two nearest-neighbouring qubits, increasing the parameter can not only induce the entanglement, but also extend the entanglement region in terms of magnetic field B and temperature T . For two next-nearest-neighbouring qubits, increasing anisotropic parameter can shift the location of the entanglement and control the extent of the entanglement in terms of magnetic field at a finite temperature.
Thermal entanglement of a two-qubit Heisenberg XYZ chain is studied.It is found that the ground state entanglement maintains a maximal constant until it drops suddenly at a critical magnetic field.Increasing the value of can extend the entanglement region in terms of temperature and magnetic field.At a finite temperature,increasing the anisotropy parameter can enhance and extend the revival entanglement when the magnetic field is beyond the critical point.These results may provide theoretical proof for manipulating the entanglement with magnetic field,strength of interaction and anisotropy parameter.
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.