Topological Basis Method for Four-Qubit Spin-$\frac {1}{2}$ XXZ Heisenberg Chain with Dzyaloshinskii-Moriya Interaction

In this paper, we investigate the four-qubit spin-\(\frac {1}{2}\) XXZ Heisenberg chain with Dzyaloshinskii-Moriya interaction by topological basis method, and research the relationship between the topological basis states and the ground states. In order to study the Hamiltonian system beyond XXZ model, we introduce two Temperley-Lieb algebra generators and two other generalized generators. Then we investigate the relationship between topological basis and Heisenberg XXZ model with Dzyaloshinskii-Moriya interaction. The results show that the ground state of this model falls on the topological basis state for anti-ferromagnetic case and gapless phase case.     

Thermal Entanglement in a Two-Qutrit Spin-1 Anisotropic Heisenberg Model

The negativity (N) as a measure of thermal entanglement (TE) is studied for a two-qutrit spin-1 anisotropic Heisenberg XXZ chain with Dzyaloshinskii-Moriya (DM)...     

具有Dzyaloshinskii-Moriya相互作用的三量子比特海森伯模型中的对纠缠

研究了一维三量子比特海森伯模型中的对纠缠的提高和控制问题,在该系统中引入了Dzyaloshinskii-Moriya（DM)相互作用,通过求解共生来计算两量子比特之间的热纠缠,结果表明：对于XXX模型,引入DM相互作用D,可以诱导铁磁和反铁磁自旋链产生热纠缠,尽管它们产生热纠缠所需的D值大小不同.对于XXZ模型,引入DM相互作用后,可以使原本不存在热纠缠的反铁磁自旋链产生纠缠,而且对于铁磁和反铁磁这两种XXZ自旋链,DM相互作用和各向异 关键词： 纠缠 XXX模型')" href="#">XXX模型 XXZ模型')" href="#">XXZ模型 Dzyaloshinskii-Moriya相互作用     

Thermal entanglement and teleportation in a two-qubit Heisenberg XXZ chain with different Dzyaloshinskii-Moriya interactions

We study the thermal output entanglement and teleportation in a two qubit Heisenberg XXZ chain with different Dzyaloshinskii-Moriya (DM) interactions. The analytical expressions of the output entanglement and the average fidelity are obtained for this model. We find the entanglement of replica states will be induced by some large value of D_z and the output entanglement exists for the case of J_z < − 1. The influences of the different DM interactions on the fidelity of teleportation are studied. We show that by introducing the x-component DM interaction, the average fidelity F_A can reach its maximum value 1.     

Teleportation via a mixture of a two qubit subsystem of a N-qubit W and GHZ state

We study the thermal entanglement in the two-qubit Heisenberg XXZ model with the Dzyaloshinskii-Moriya (DM) interaction, and teleport an unknown state using the model in thermal equilibrium state as a quantum channel. The effects of DM interaction, including D_x and D_z interaction, the anisotropy and temperature on the entanglement and fully entangled fraction are considered. What deserves mentioning here is that for the antiferromagnetic case, the D_x interaction can be more helpful for increasing the entanglement and critical temperature than D_z, but this cannot for teleportation.     

Thermodynamic properties of Heisenberg model for magnetic ordered graphene sheet

We study the thermodynamic properties of two dimensional Heisenberg antiferromagnet on the honeycomb lattice in the presence of anisotropic Dzyaloshinskii-Moriya interaction and next nearest neighbor coupling exchange constant. A sublattice antiferromagnetic long range ordering has been considered for localized electrons on honeycomb lattice structure. In particular, the temperature dependence of specific heat has been investigated for various physical parameters in the model Hamiltonian. Using Holstein-Primakoff bosonic transformations, the behavior of thermodynamic properties has been studied by means of excitation spectrum of mapped bosonic gas. Furthermore we have studied the dependence of specific heat and magnetization on Dzyaloshinskii-Moriya interaction strength for various next nearest neighbor interaction strengths. At low temperatures, the specific heat is found to be monotonically increasing with temperature. We have found the dependence of specific heat on Dzyaloshinskii-Moriya interaction strength shows a monotonic increasing behavior for various next nearest neighbor exchange constants. Also we have studied the temperature dependence of staggered magnetization for different next nearest neighbor coupling constants. Our results show the critical temperature moves to higher amounts with reduction of Dzyaloshinskii-Moriya interaction strength.     

Ground-State and Thermal Entanglement in Three-Spin Heisenberg-XXZ Chain with Three-Spin Interaction

The entanglement properties of a three-spin X X Z Heisenberg chain with three-spin interaction are studied by means of concurrence of pairwise entanglement. We show that ground-state pairwise entanglement, pairwise thermal entanglement, or quantum phase transition is not present in antiferromagnetic spin chain. For the ferromagnetic case, quantum phase transition takes place at △ = 1 for anisotropic interaction and at some values of three-spin coupling strength, and pairwise thermal entanglement increases when the value of J/T increases and with anisotropic interaction and three-spin interaction decrease. In addition, we find that increasing the anisotropic interaction and the three-spin interaction will decrease critical temperature.     

Ground-State and Thermal Entanglement in Three-Spin Heisenberg-XXZ Chain with Three-Spin Interaction

The entanglement properties of a three-spin X X Z Heisenberg chain with three-spin interaction are studied by means of concurrence of pairwise entanglement. We show that ground-state pairwise entanglement, pairwise thermal entanglement, or quantum phase transition is not present in antiferromagnetic spin chain. For the ferromagnetic case, quantum phase transition takes place at A = 1 for anisotropic interaction and at some values of three-spin coupling strength, and pairwise thermal entanglement increases when the value of J/T increases and with anisotropic interaction and three-spin interaction decrease. In addition, we find that increasing the anisotropic interaction and the three-spin interaction will decrease critical temperature.     

Thermal Entanglement in Anisotropic Heisenberg XYZ Chain with External Magnetic Field at Any Finite <Emphasis Type="Italic">T</Emphasis>

The thermal entanglement of a Two-qubit anisotropic Heisenberg XYZ chain in thermal equilibrium at temperature T in the presence of external magnetic field is investigated, the combined influence of anisotropic interaction and the inhomogeneous magnetic field on the thermal entanglement of the system is examined. Our results show that, the thermal entanglement can be produced at any finite T by adjusting the magnetic field strength, and the critical magnetic field ε for which the concurrence C vanishes is increased by introducing the interaction of the z-component of two neighboring spins J _z , and by the increasing of the anisotropic parameter γ.     

Thermal Entanglement of the Two-Qubit Heisenberg Spin Chain Coupled to a Single-Mode Cavity Field

Thermal entanglement of a two-qubit Heisenberg spin chain coupled to a single-mode cavity field is investigated. It is found that (1) thermal entanglement without the rotating-wave approximation (RWA) is explicitly smaller than that obtained with the RWA, which means that the counter-rotating terms have a large impact on thermal entanglement, therefore they cannot be neglected; (2) the case (ω≪Ω) is more beneficial for enhancing thermal entanglement than the resonance case (ω=Ω), the near-resonant case (ω≈Ω) and the case (ω≫Ω); (3) for thermal entanglement, there is a competition process between the exchange coupling J (the direct-coupling between the two two-level atoms) and the coupling constant g (which deduces the indirect effect between the two two-level atoms); the critical value of g increases with the spin coupling strength J.     

Two-Player 2 × 2 Quantum Game in Spin System

In this work, we study the payoffs of quantum Samaritan’s dilemma played with the thermal entangled state of XXZ spin model in the presence of Dzyaloshinskii-Moriya (DM) interaction. We discuss the effect of anisotropy parameter, strength of DM interaction and temperature on quantum Samaritan’s dilemma. It is shown that although increasing DM interaction and anisotropy parameter generate entanglement, players payoffs are not simply decided by entanglement and depend on other game components such as strategy and payoff measurement. In general, Entanglement and Alice’s payoff evolve to a relatively stable value with anisotropy parameter, and develop to a fixed value with DM interaction strength, while Bob’s payoff changes in the reverse direction. It is noted that the augment of Alice’s payoff compensates for the loss of Bob’s payoff. For different strategies, payoffs have different changes with temperature. Our results and discussions can be analogously generalized to other 2 × 2 quantum static games in various spin models.     

具有Dzyaloshinskii-Moriya相互作用的一维随机量子XY模型中的纠缠特性

研究了一维随机量子XY自旋链中中心两量子位的纠缠特性,在该系统中引入了自旋间的交换耦合杂质、磁杂质和Dzyaloshinskii-Moriya相互作用,并且杂质满足高斯分布关系.通过数值计算,求出了自旋的关联函数和平均磁化强度,给出了Concurrence的解析表达式.结果表明：高斯分布和Dzyaloshinskii-Moriya相互作用对两量子位的纠缠有重要的影响,选择合适的交换耦合、外界磁场和Dzyaloshinskii-Moriya相互作用参数,可以控制和提高中心两量子位的纠缠. 关键词： 纠缠 XY模型')" href="#">随机量子XY模型 高斯分布 Dzyaloshinskii-Moriya相互作用     

Thermal entanglement and teleportation of a thermally mixed entangled state of a Heisenberg chain through a Werner state

The thermal entanglement and teleportation of a thermally mixed entangled state of a two-qubit Heisenberg XXX chain under the Dzyaloshinski Moriya （DM） anisotropic antisymmetric interaction through a noisy quantum channel given by a Werner state is investigated. The dependences of the thermal entanglement of the teleported state on the DM coupling constant, the temperature and the entanglement of tbe noisy quantum channel are studied }n detail for both the ferromagnetic and the antiferromagnetic cases. The result shows that a minimum entanglement of the noisy quantum channel must be provided in order to realize the entanglement teleportation. The values of fidelity of the teleported state are also studied for these two cases. It is found that under certain conditions, we can transfer an initial state with a better fidelity than that for any classical communication protocol.     

Thermal Quantum Discord in Anisotropic Heisenberg XXZ Model withDzyaloshinskii-Moriya Interaction

The thermal quantum discord (QD) is studied in a two-qubit Heisenberg XXZ system with Dzyaloshinskii-Moriya (DM) interaction. We compare the thermal QD with thermal entanglement in this system and find remarkable differences between them. For instance, we show situations where QD decreases asymptotically to zero with temperature T while entanglement decreases to zero at the point of critical temperature, situations where QD decreases with certain tunable parameters such as D_z and D_x when entanglement increases. We find that the characteristic of QD is exotic in this system and this possibly offers a potential solution to enhance entanglement of a system. We also show that tunable parameter D_x is more efficient than parameter D_z in most regions for controlling the QD.     

Effects of interaction of nanoparticles in a highly anisotropic ferrimagnet

This paper reports on a study of the field and temperature dependences of the parameters of the particle magnetic interaction in a densely packed system of nanocrystals of the highly anisotropic hexagonal ferrite BaFe₁₂O₁₉ with the particles distributed in diameter within the range 10—100 nm and having volumes satisfying the criterion of “small Stoner—Wohlfarth particles.” It is shown that the resultant particle interaction in the temperature range 300 K≤T≤640 K has a negative sign, whereas for T>640 K, it is positive. The maximum values of the parameter Δm allow classification of the interaction as moderate in strength. The temperature dependences of the interaction parameters are found to correlate with manifestation of the size and surface effects in the system, which are characteristic of small particles (transition to the superparamagnetic state, “surface” anisotropy, and reduced exchange interaction in a structurally defective near-surface layer of particles).     

The Lieb-Liniger Model as a Limit of Dilute Bosons in Three Dimensions

We show that the Lieb-Liniger model for one-dimensional bosons with repulsive δ-function interaction can be rigorously derived via a scaling limit from a dilute three-dimensional Bose gas with arbitrary repulsive interaction potential of finite scattering length. For this purpose, we prove bounds on both the eigenvalues and corresponding eigenfunctions of three-dimensional bosons in strongly elongated traps and relate them to the corresponding quantities in the Lieb-Liniger model. In particular, if both the scattering length a and the radius r of the cylindrical trap go to zero, the Lieb-Liniger model with coupling constant g ~ a/r ² is derived. Our bounds are uniform in g in the whole parameter range 0 ≤ g ≤ ∞, and apply to the Hamiltonian for three-dimensional bosons in a spectral window of size ~ r ⁻² above the ground state energy. ?2008 by the authors. This paper may be reproduced, in its entirety, for non-commercial purposes.     

Thermal entanglement in the anisotropic Heisenberg model with Dzyaloshinskii-Moriya interaction in an inhomogeneous magnetic field

The thermal entanglement of a two-qubit anisotropic Heisenberg XXZ chain with Dzyaloshinskii-Moriya (DM) interaction in an inhomogeneous magnetic field was studied in detail. The effects of the DM parameter, external magnetic field (B), a parameter b which controls the inhomogeneity of B and the bilinear interaction parameters J_x = J_y ≠ J_z (the anisotropic case) on the concurrence (C) was formulated and studied in detail. The behaviors of the concurrences for the cases between (J = J_z = 1) and (J = -1,J_z = 1) and, (J = J_z = -1) and (J = 1,J_z = -1) at the ground state and at the thermal equilibrium are exactly the same. It was found that for the antiferromagnetic (AFM) case the entanglements persist to higher temperatures in comparison with the ferromagnetic (FM) case. In addition, the AFM case presents a special point at which the nonzero concurrences are all equal at some special temperatures. The further properties will be given in the text.     

Entanglement evolution in an anisotropic two-qubit Heisenberg XYZ model with Dzyaloshinskii-Moriya interaction

This paper investigates the entanglement evolution of a two-qubit anisotropic Heisenberg XYZ chain in the presence of Dzyaloshinskii-Moriya interaction.The time evolution of the concurrence is studied for the initial pure entangled states cos θ |00 + sin θ |11 and cos |01 + sin |10 at zero temperature.The influences of Dzyaloshinskii-Moriya interaction D,anisotropic parameter and environment coupling strength γ on entanglement evolution are analysed in detail.It is found that the effect of noisy environment obviously suppresses the entanglement evolution,and the Dzyaloshinskii-Moriya interaction D acts on the time evolution of entanglement only when the initial state is cos |01 + sin |10.Finally,a formula of steady state concurrence is obtained,and it is shown that the stable concurrence,which is independent of different initial states and Dzyaloshinskii-Moriya interaction D,depends on the anisotropic parameter and the environment coupling strength γ.     

在不同初态下Dzyaloshinskii-Moriya相互作用及内禀退相干对海森伯系统的量子纠缠的影响

研究了存在内禀退相干时,对于不同的系统初态,具有DM相互作用和各向异性的三粒子XXZ海森伯模型的对纠缠动力学特性.得出了一些结论:系统的对纠缠度与各向异性参数?无关,但内禀退相干对系统的纠缠有明显的抑制作用;在内禀退相干存在时,若系统初态为纠缠态,选择合适的DM相互作用的参数,系统的对纠缠有一个非零的稳定值;系统初态为分离态时,系统的对纠缠会随时间震荡衰减,并且每次震荡会出现纠缠突然死亡现象,系统的对纠缠最终达到解纠缠状态.因此,选择合适的系统初态和DM相互作用参数可以有效地控制系统的对纠缠.     

Dzyaloshinskii-Moriya相互作用对量子XY链中热纠缠的影响

研究了Dzyaloshinskii-Moriya(DM)相互作用对混合自旋(1/2,3/2)XY链以及自旋为1的XY链热纠缠的影响.通过计算两粒子之间的纠缠,发现它不仅能够增强纠缠,而且能使两粒子之间的纠缠度达到一稳定值;当温度较高时,要使热纠缠达到稳定值需要更强的这种相互作用.在相同的条件下,自旋s=1的两粒子之间的纠缠要小于混合自旋两粒子之间的纠缠.粒子之间的交换耦合相互作用有助于加强粒子之间的热纠缠,因此可以与DM相互作用一起调节纠缠度.当交换耦合相互作用比 关键词： 量子纠缠 XY 模型')" href="#">XY 模型 negativity Dzyaloshinskii-Moriya相互作用