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

Communications in Theoretical Physics

Entanglement of a Five-Qubit HeisenbergX XChain in a Magnetic Field

Min Cao, Ling Yin-Sheng, Zhu Shi-Qun

Published May 1, 2009• 0 citations
Publisher

Abstract

We calculate the eigenvalues and eigenvectors of a five-qubit isotropic Heisenberg model in an external magnetic field, and give analytical results for the concurrence of two nearest-neighbor qubits. A magnetic field can eliminate degeneration and change the ground state of the system. Therefore increasing the value of the magnetic field can induce entanglement in a certain range both for the antiferromagnetic and ferromagnetic case.

DOI
10.1088/0253-6102/51/5/10

Related papers

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

Min Cao, Shiqun Zhu

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.

arXiv:quant-ph/0501029•Physical Review A•Mar 24, 2005•61 citations

Entanglement in the XZ spin chain model in the external magnetic field

F. Soheilian, Mohammad Reza Soltani, M Firoozi +1 more

The entanglement at zero-temperature is studied in a two-qubit XZ spin-1/2 chain model in an external magnetic field which is applied in the z direction. We have obtained an analytical relation for the effect of the external magnetic field on the concurrence. It is shown that the ground state of the system depends on the strength of exchange coupling. We have shown that the analytical relation of the concurrence is independent of Jz. It is shown that for Jz >0 the concurrence is depended on the critical value of the external magnetic field and it is changed at the critical external magnetic field. Also we have shown that for h hc, the concurrence decreases by increasing the external magnetic field. For Jz <0, the concurrence decreases by increasing the external magnetic field.

Journal of Physical & Theoretical Chemistry•Dec 1, 2014•0 citations

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

Entanglement in the quantum Heisenberg XY model

Xiaoguang Wang

We study the entanglement in the quantum Heisenberg $\mathrm{XY}$ model in which the so-called W entangled states can be generated for 3 or 4 qubits. By the concept of concurrence, we study the entanglement in the time evolution of the $\mathrm{XY}$ model. We investigate the thermal entanglement in the two-qubit isotropic $\mathrm{XY}$ model with a magnetic field and in the anisotropic $\mathrm{XY}$ model, and find that the thermal entanglement exists for both ferromagnetic and antiferromagnetic cases. Some evidences of the quantum phase transition also appear in these simple models.

arXiv:quant-ph/0101013•Physical Review A•Jun 12, 2001•576 citations

Ground State Entanglement in Spin Systems

Hironori Yano, Hidetoshi Nishimori

We study the entanglement between arbitrary two spins in the XY and the antiferromagnetic Heisenberg spin chains in a uniform magnetic field.The entanglement of pairwise qubits in these models is obtained as a function of magnetic field by exact and numerical calculations.We find that the behavior of entanglement in the isotropic XY model is qualitatively the same as that in the Heisenberg model.Properties of entanglement length are also discussed.

Progress of Theoretical Physics Supplement•Jan 1, 2005•8 citations

Thermal entanglement in the system consisting of spin 1/2 and spin S

Mao-Fa Fang

Quantum thermal entanglement of two next nearest-neighbor qubits in a four-qubit isotropic Heisenberg XY model consisting of spin 1/2 and spin S in a homogeneous external magnetic field B was investigated by concurrence measure of entanglement.The results show that the external magnetic field can induce the thermal entanglement of two next nearest-neighbor qubits.The amplitude of thermal entanglement is dependent on the spin S,temperature T and homogeneous external magnetic field B.As a result,it is feasible to control thermal entanglement by adjusting the value of external magnetic field B.When S is sufficiently large,the threshold temperature above which there is no thermal entanglement may also be very high.The feature can be used in high-temperature entanglement of condensed matter systems and it will be useful in the research of quantum information in solid systems.

Chinese Journal of Quantum Electronics•Jan 1, 2008•0 citations
We calculate the eigenvalues and eigenvectors of a five-qubit isotropic Heisenberg model in an external magnetic field, and give analytical results for the concurrence of two nearest-neighbor qubits. A magnetic field can eliminate degeneration and change the ground state of the system. Therefore increasing the value of the magnetic field can induce entanglement in a certain range both for the antiferromagnetic and ferromagnetic case.
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 entanglement at zero-temperature is studied in a two-qubit XZ spin-1/2 chain model in an external magnetic field which is applied in the z direction. We have obtained an analytical relation for the effect of the external magnetic field on the concurrence. It is shown that the ground state of the system depends on the strength of exchange coupling. We have shown that the analytical relation of the concurrence is independent of Jz. It is shown that for Jz >0 the concurrence is depended on the critical value of the external magnetic field and it is changed at the critical external magnetic field. Also we have shown that for h hc, the concurrence decreases by increasing the external magnetic field. For Jz <0, the concurrence decreases by increasing the external magnetic field.
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 the entanglement in the quantum Heisenberg XY\mathrm{XY}XY model in which the so-called W entangled states can be generated for 3 or 4 qubits. By the concept of concurrence, we study the entanglement in the time evolution of the XY\mathrm{XY}XY model. We investigate the thermal entanglement in the two-qubit isotropic XY\mathrm{XY}XY model with a magnetic field and in the anisotropic XY\mathrm{XY}XY model, and find that the thermal entanglement exists for both ferromagnetic and antiferromagnetic cases. Some evidences of the quantum phase transition also appear in these simple models.
Quantum thermal entanglement of two next nearest-neighbor qubits in a four-qubit isotropic Heisenberg XY model consisting of spin 1/2 and spin S in a homogeneous external magnetic field B was investigated by concurrence measure of entanglement.The results show that the external magnetic field can induce the thermal entanglement of two next nearest-neighbor qubits.The amplitude of thermal entanglement is dependent on the spin S,temperature T and homogeneous external magnetic field B.As a result,it is feasible to control thermal entanglement by adjusting the value of external magnetic field B.When S is sufficiently large,the threshold temperature above which there is no thermal entanglement may also be very high.The feature can be used in high-temperature entanglement of condensed matter systems and it will be useful in the research of quantum information in solid systems.