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1.
Bipartite entanglement in a two-qubit Heisenberg XXZ chain under an inhomogeneous magnetic field 总被引:1,自引:1,他引:0
This paper investigates the bipartite entanglement of a two-qubit Heisenberg XXZ chain under an inhomogeneous magnetic field. By the concept of negativity, we find that the inhomogeneity of the magnetic field may induce entanglement and the critical magnetic field is independent of Jz. We also find that the entanglement is symmetric with respect to a zero magnetic field. The anisotropy parameter Jz may enhance the entanglement. 相似文献
2.
Entanglement in a two-qubit Heisenberg XXZ chain with different Dzyaloshinskii-Moriya couplings and an inhomogeneous magnetic field
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Ground state entanglement and thermal entanglement of a two-qubit Heisenberg XXZ chain in the presence of the different Dzyaloshinski-Moriya interaction and inhomogeneous magnetic field are investigated.By the concept of concurrence, we find that the inhomogeneity of the magnetic field may make entanglement last for a long time and the critical temperature is dependent on Jz and b. The entanglement can be increased by increasing the temperature in some cases. We also find that the x-component parameter Dx has a higher critical temperature and more entanglement for a certain condition than the z-component parameter Dz. 相似文献
3.
G.-F. Zhang S.-S. Li 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,37(1):123-127
The thermal entanglement in a two-spin-qutrit system with two
spins coupled by exchange interaction under a magnetic field in an
arbitrary direction is investigated. Negativity, the measurement
of entanglement, is calculated. We find that for any temperature
the evolvement of negativity is symmetric with respect to magnetic
field. The behavior of negativity is presented for four different
cases. The results show that for different temperature, different
magnetic field give maximum entanglement. Both the parallel and
antiparallel magnetic field cases are investigated qualitatively
(not quantitatively) in detail, we find that the entanglement may
be enhanced under an antiparallel magnetic field. 相似文献
4.
SHAO Bin ZENG Tian-Hai ZOU Jian 《理论物理通讯》2005,44(2):255-258
Taking the intrinsic decoherence effect into account, we investigate the time evolution of entanglement for two-qubit XYZ Heisenberg model in an external uniform magnetic field. Concurrence, the measurement of entanglement,is calculated. We show how the intrinsic decoherence modifies the time evolution of the entanglement and find that at short-time case, concurrence is oscillating as increasing magnetic field, which implies that entanglement may be enhanced or weakened in some time regions. 相似文献
5.
SHAO Bin ZENG Tian-Hai ZOU Jian 《理论物理通讯》2005,44(8)
Taking the intrinsic decoherence effect into account, we investigate the time evolution of entanglement for two-qubit XYZ Heisenberg model in an external uniform magnetic field. Concurrence, the measurement of entanglement,is calculated. We show how the intrinsic decoherence modifies the time evolution of the entanglement and find that at short-time case, concurrence is oscillating as increasing magnetic field, which implies that entanglement may be enhanced or weakened in some time regions. 相似文献
6.
The thermal entanglement in a two-spin-qutrit system with two spins coupled by exchange interaction is investigated in terms of the measure of entanglement called ‘negativity’. We strictly show that for any temperature the entanglement is symmetric with respect to zero magnetic field. The behavior of negativity is presented for four different cases. We find that the entanglement may be enhanced under a nonuniform magnetic field. Because there is not any necessary and sufficient condition for quantum separability in systems of dimension 3⊗3, our results are qualitative, not quantitative. 相似文献
7.
在一维倾斜场伊辛模型中, 利用并发度和Q测量函数分别对系统的两体纠缠和整体纠缠进行度量, 通过讨论系统中量子纠缠的动力学特性, 能够体现出系统的可积和不可积行为. 由系统基态的纠缠特性可以发现只要倾角不为零时, 系统的Q测量函数会随着磁场的增大而减少, 而用并发度刻画的系统的相变特性, 随着磁场倾角的增大发生了变化. 考虑系统的动力学行为发现, 在一维倾斜场伊辛模型中, 不可积性会抑制两体纠缠, 却促进系统整体纠缠生成.
关键词:
伊辛模型
不可积性
两体纠缠
整体纠缠 相似文献
8.
Pairwise thermal entanglement in a three-qubit Heisenberg XX model with a nonuniform magnetic field and Dzyaloshinski-- Moriya interaction
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Pairwise thermal entanglement in a three-qubit Heisenberg XX model is investigated when a nonuniform magnetic field and the Dzyaloshinski-Moriya interaction are included. We find that the nonuniform magnetic field and Dzyaloshinski-Moriya interaction are the more efficient control parameters for the increase of entanglement and critical temperature. For both the nearest neighbour sites and the next nearest neighbour sites, the magnetic field can induce entanglement to a certain extent and the Dzyaloshinski-Moriya interaction can enhance the entanglement to a stable value. The steady value of the nearest neighbour site entanglement C 12 is larger than the next nearest neighbour site entanglement C 13 . An interesting phenomenon is that the entanglement curve of C 12 appears a peak value when the Dzyaloshinski-Moriya interaction is considered in a nonuniform magnetic field. 相似文献
9.
Maximizing Thermal Entanglement of XY Model Using Site-Dependent Magnetic Fields in Specific Directions
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We study the thermal entanglement by means of concurrence in a two-qubit isotropic XY model in the presence of site-dependent external magnetic fields in arbitrary directions. We find that at a given temperature and magnetic field strength, the mirror symmetry of the two fields about the x-y plane is a necessary condition for maximum entanglement. However, if there is no constraint on the field strengths, then the necessary condition for maximum entanglement reduces to the configuration that the two fields are vertical, anti-parallel and with the same strength. We also investigate the anisotropic XY model and find that the above conclusion more or less holds. 相似文献
10.
11.
Y. Zhou G.-F. Zhang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(2):227-231
We study quantum teleportation via a two-qubit Heisenberg
XXZ chain under an inhomogeneous magnetic field. We first consider entanglement
teleportation, and then focus on the teleportation fidelity under different
conditions. The effects of anisotropy and the magnetic field, both uniform
and inhomogeneous, are discussed. We also find that, though entanglement
teleportation does require an entangled quantum channel, a nonzero critical
value of minimum entanglement is not always necessary. 相似文献
12.
Seyit Deniz Han Tuĝba Tüfekçi Timothy P. Spiller Ekrem Aydiner 《International Journal of Theoretical Physics》2017,56(5):1474-1483
In this study, we investigate entanglement in a two mixed-spin (1/2,1) XY Heisenberg spin system under an applied magnetic field by considering the long-range interaction with an inverse-square function. The spin-spin coupling constant is considered as a function of the distance between spins. We also discuss the temperature and magnetic field dependence of the thermal entanglement in this system for this interaction. The numerical results show that, in the presence of the long-range interaction, thermal entanglement between spins has a rich behavior dependent upon the interaction strength, temperature and magnetic field. We find that for less than a critical distance there are entanglement plateaus dependent upon the distance between spins, whereas above the critical distance the entanglement can exhibit sudden death. 相似文献
13.
GUO Jin-Liang NIE Jing SONG He-Shan 《理论物理通讯》2008,49(6):1435-1438
We consider a two-qubit Heisenberg XXZ chain as a resource for quantum teleportation via the standard teleportation protocol To. The effects of anisotropic on teleportation fidelity and entanglement are studied in detail. We find anisotropic not only improves the criticM temperature Tc and criticM magnetic field Bc, beyond which quantum teleportation is inferior to classicM communication protocol, but also enhances the fidelity for fixed magnetic field B and temperature T. For entanglement teleportation, the effects of magnetic field on average fidelity and output entanglement are studied. 相似文献
14.
本文研究了Na_9[Cu_3Na_3(H_2O)_9(α-As W_9O_(33))_2]·26H_2O(简记为{Cu_3})单分子磁体在热平衡和外加磁场作用下的三体纠缠性质,利用等效自旋模型和实验拟合参数,数值计算了{Cu_3}型三角自旋环中三体负性纠缠度(tripartite negativity).分别考虑沿垂直于三角自旋环方向的磁场、平行于三角自旋环方向的磁场,以及倾斜磁场的情形.结果表明,磁场的方向、大小以及温度对系统三体负性纠缠度有着重要影响.文中给出了在不同磁场方向下,临界温度随磁场强度的变化图,由此可以得到三体纠缠存在的参数区域.同时发现在特定的参数区域,该系统存在纠缠恢复现象.因此适当调节温度、磁场强度大小和磁场方向可以有效调控{Cu_3}型三角自旋环中的三体纠缠性质. 相似文献
15.
研究了具有三角自旋环的伊辛-海森伯链在磁场作用下的热纠缠性质.分别讨论了三角自旋环中自旋1/2粒子间相互作用的三种情形,即XXX,XXZ和XY Z海森伯模型.利用转移矩阵方法,数值计算了具有三角自旋环的伊辛-海森伯链的配对纠缠度.计算结果表明,外加磁场强度和温度对系统处于上述三种海森伯模型的热纠缠性质均有重要影响.给出了系统在不同的海森伯模型下,纠缠消失对应的临界温度随磁场强度的变化图,由此可以得到系统存在配对纠缠的参数区域,同时发现在特定的参数区域存在纠缠恢复现象.因此适当调节温度和磁场强度,可以有效调控具有三角自旋环的伊辛-海森伯链热纠缠性质. 相似文献
16.
We study the entanglement in anisotropic
(1/2,1) mixed-spin Heisenberg XY model under the presence of an external magnetic field at thermal equilibrium. By adjusting the anisotropic parameter and the magnetic field, one is able to obtain entanglement at higher temperature. We find the evidence of the
quantum phase transition in the model and observe that the quantum
phase transition point at low temperature moves toward weak magnetic
field with the increase of the anisotropic parameter. 相似文献
17.
GUO KeTao LIANG MingChao XU HongYu & ZHU ChengBo School of Applied Science Jiangxi University of Science Technology Ganzhou China 《中国科学:物理学 力学 天文学(英文版)》2011,(3)
By using the concept of negativity, we investigate the thermal entanglement of a two-spin (1/2, 3/2) mixed-spin Heisenberg XX chain with an inhomogeneous external magnetic field. We obtain the analytical results of entanglement of this model. For the case of uniform magnetic field, we find that the critical temperature is higher than the results of the spin-1/2 chain and (1/2,1) mixed-spin chain. And by adjusting the nonuniform parameter b, one is able to obtain more entanglement at a higher temperature. 相似文献
18.
G. Lagmago Kamta A. Y. Istomin A. F. Starace 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):389-400
We study systematically the entanglement of a two-qubit
Heisenberg XY model in thermal equilibrium in the presence of an
external arbitrarily-directed static magnetic field, thereby
generalizing our prior work [G. Lagmago Kamta, A.F. Starace, Phys.
Rev. Lett. 88, 107901 (2002)]. We show that a magnetic field
having a component in the xy-plane containing the spin-spin
interaction components produces different entanglement for
ferromagnetic (FM) and antiferromagnetic (AFM) couplings. In
particular, quantum phase transitions induced by the magnetic
field-driven level crossings always occur for the AFM-coupled
qubits, but only occur in FM-coupled qubits when the coupling is of
Ising type or when the magnetic field has a component perpendicular
to the xy-plane. When the magnetic field has a component in the
xy-plane, the cut-off temperature above which the entanglement of
both the FM- and AFM-coupled qubits vanishes can always be
controlled using the magnetic field for any value of the XY coupling
anisotropy parameter. Thus, by adjusting the magnetic field, an
entangled state of two spins can be produced at any finite
temperature. Finally, we find that a higher level of entanglement is
achieved when the in-plane component of the magnetic field is
parallel to the direction in which the XY exchange coupling is
smaller. 相似文献
19.
Sudden Death, Birth and Stable Entanglement in a Two-Qubit Heisenberg XY Spin Chain 总被引:1,自引:0,他引:1
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Taking the decoherence effect due to population relaxation into account, we investigate the entanglement properties for two qubits in the Heisenberg XY interaction and subject to an external magnetic field. It is found that the phenomenon of entanglement sudden death (ESD) as well as sudden birth (ESB) appear during the evolution process for particular initial states. The influence of the external magnetic field and the spin environment on ESD and ESB are addressed in detail. It is shown that the concurrence, a measure of entanglement, can be controlled by tuning the parameters of the spin chain, such as the anisotropic parameter, external magnetic field, and the coupling strength with their environment. In particular, we find that a critical anisotropy constant exists, above which ESB vanishes while ESD appears. It is also notable that stable entanglement, which is independent of different initial states of the qubits, occurs even in the presence of decoherence. 相似文献
20.
研究了匀强及非匀强磁场中反铁磁体Heisenberg XXX链的近邻和次近邻纠缠.结果表明对基态情形,纠缠随磁场B变化呈现阶梯型结构,这可用来构建量子纠缠"放大器"或量子纠缠"开关".对有限温度情形,引进一非匀强磁场Bi=(-1)iB可以使近邻格点间纠缠在某些区域明显增大,而次近邻格点间纠缠则完全消失;同时引进非匀强磁场Bi=(-1)iB还可以使近邻格点纠缠的临界温度Tcn增大,且Tcn随B的增大而升高,这意味着我们可以通过调节B的大小而在任意温度下得到纠缠. 相似文献