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1.
Teleportation and thermal entanglement in two-qubit Heisenberg X Y Z spin chain with the Dzyaloshinski-Moriya interaction and the inhomogeneous magnetic field 下载免费PDF全文
This paper studies the average fidelity of teleportation and thermal entanglement for a two-qubit Heisenberg X Y Z chain in the presence of both an inhomogeneous magnetic field and a Dzyaloshinski-Moriya interaction. It shows that for a fixed Dz, the increase of bz will broaden the critical temperature at the cost of decreasing the thermal entanglement. And it can modulate the inhomogeneous magnetic field and the Dzyaloshinski-Moriya interaction for the average fidelity of teleportation to be optimal. 相似文献
2.
Pairwise thermal entanglement in a three-qubit Heisenberg XX model with a nonuniform magnetic field and Dzyaloshinski-- Moriya interaction 下载免费PDF全文
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
3.
4.
Chun-Lei Jiang Mao-Fa Fang Yao-Hua Hu 《International Journal of Theoretical Physics》2009,48(6):1672-1677
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. 相似文献
5.
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
6.
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
7.
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
8.
Thermal entanglement in a mixed-spin Heisenberg XXZ model under a nonuniform external magnetic field
The thermal entanglement in (1/2,1) mixed-spin Heisenberg XXZ model is investigated under an external nonuniform magnetic
field. In the uniform magnetic field system, the critical magnetic field B
c and critical temperature T
c are increased by increasing the anisotropic parameter k. The degree of magnetic field b plays an important role in improving the critical temperature and enlarging the region of entanglement in the nonuniform
magnetic field system. 相似文献
9.
10.
In this paper, the entanglement in a mixed-spin (1/2, 3/2) Heisenberg XXZ model with Dzyaloshinskii-Moriya (DM) interaction in an inhomogeneous external magnetic field is studied. We not only calculate the ground-state entanglement but also investigate the behaviors of quantum phase transition following the changes of DM interaction and nonuniform magnetic field. More importantly, we note that the DM interaction improves the critical magnetic field B c , the critical temperature T c and broadens the region of entanglement. 相似文献
11.
D. C. Li Z. L. Cao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,50(2):207-214
We investigate the entanglement in a two-qubit Heisenberg XYZ
system with different Dzyaloshinskii-Moriya (DM) interaction and
inhomogeneous magnetic field. It is found that the control
parameters (Dx, Bx and bx) are remarkably different
with the common control parameters (Dz, Bz and bz)
in the entanglement and the critical temperature, and these
x-component parameters can increase the entanglement and the
critical temperature more efficiently. Furthermore, we show the
properties of these x-component parameters for the control of
entanglement. In the ground state, increasing Dx (spin-orbit
coupling parameter) can decrease the critical value bxc and
increase the entanglement in the revival region, and adjusting
some parameters (increasing bx and J, decreasing Bx
and Δ) can decrease the critical value Dxc to enlarge
the revival region. In the thermal state, increasing Dx can
increase the revival region and the entanglement in the revival
region (for T or bx), and enhance the critical value
Bxc to make the region of high entanglement larger. Also, the
entanglement and the revival region will increase with the
decrease of Bx (uniform magnetic field). In addition, small
bx (nonuniform magnetic field) has some similar properties to
Dx, and with the increase of bx the entanglement also
has a revival phenomenon, so that the entanglement can exist at
higher temperature for larger bx. 相似文献
12.
We study the time evolution of entanglement of two spins in an anisotropically coupled quantum dot interacting with the unpolarised nuclear spins environment. We assume that the exchange coupling strength in the z direction J z is different from the lateral one J l . We observe that the entanglement decays as a result of the coupling to the nuclear environment and reaches a saturation value, which depends on the value of the exchange interaction difference J = ‖J l ? J z ‖ between the two spins and the strength of the applied external magnetic field. We find that the entanglement exhibits a critical behaviour controlled by the competition between the exchange interaction J and the external magnetic field. The entanglement shows a quasi-symmetric behaviour above and below a critical value of the exchange interaction. It becomes more symmetric as the external magnetic field increases. The entanglement reaches a large saturation value, close to unity, when the exchange interaction is far above or below its critical value and a small one as it closely approaches the critical value. Furthermore, we find that the decay rate profile of entanglement is linear when the exchange interaction is much higher or lower than the critical value but converts to a power law and finally to a Gaussian as the critical value is approached from both directions. The dynamics of entanglement is found to be independent of the exchange interaction for an isotropically coupled quantum dot. 相似文献
13.
Guo-Hui Yang Yong-Hong Ma Di Mei Ling Zhou 《International Journal of Theoretical Physics》2008,47(7):1836-1843
By introducing the nonuniform magnetic field, we investigate the entanglement teleportation via two-qubit Heisenberg chain.
We show that for ferromagnetic chain, the opposite direction magnetic field on the two-qubit chain can excite the teleported
entanglement C
out, while the uniform magnetic field can not do it. The effect of the uniform magnetic field B and the nonuniform magnetic field b on the threshold temperature T
c
is also plotted. Our study on the average fidelity of this quantum channel system shows that the magnetic field in opposite
direction can result in the ideal average fidelity no matter whether the chain is ferromagnetic or antiferromagnetic. 相似文献
14.
通过负值度和测量诱导的扰动, 研究了非均匀磁场和杂质磁场对自旋为1的Heisenberg系统量子关联的影响. 研究发现非均匀磁场的增加会降低纠缠, 但也可用来产生纠缠, 并且会提高临界非线性作用Kc的值, 测量诱导的扰动的临界磁场要高于负值度的临界磁场, 而且测量诱导的扰动不会随着非线性作用|K| 的减小而消失, 它能全面反映量子关联的存在. 研究还发现, 不同杂质磁场对测量诱导的扰动的影响彼此间无交叉. 杂质磁场下, 相互作用|J| 必须小于非线性作用|K| 才会有纠缠存在, 但是测量诱导的扰动却可以在相互作用|J| 大于非线性作用|K| 时依然存在, |J| 与|K| 相同时只是测量诱导的扰动的最小取值点. 此外, 系统粒子数目对量子关联也具有重要影响. 相似文献
15.
Entanglement in a two-qubit Heisenberg XXZ chain with different Dzyaloshinskii-Moriya couplings and an inhomogeneous magnetic field 下载免费PDF全文
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
16.
研究了非匀强磁场中各向异性Heisenberg XY链的基态纠缠和热纠缠.结果表明对双量子位情形,纠缠与格点间耦合常数J、外部磁场B、各向异性参数γ和b的正负无关.对绝对零度情形,我们给出了纠缠C的解析表达式,并指出临界磁场Bc随磁场各向异性参数b的增大而增大.对有限温度情形,我们给出了γ=0时C的解析表达式和γ≠0时的数值模拟结果,结果发现引进非匀强磁场可以使纠缠在某些区域明显增大;同时我们还指出当γ=0时,纠缠存在的临界温度Tc仅是b的增函数,而当γ≠0时,它却由B和b共同决定. 相似文献
17.
The thermal entanglement in a two-qubit Heisenberg XXZ spin chain is investigated under a single pulse magnetic field Bsinθ. The paper shows that the greater the contribution of the inhomogeneity on the exchange interaction, the higher thermal entanglement will be attained at the fixed temperature except the case that $\theta=2k\pi+\frac{3}{2}\pi$ . J z significantly disturb the thermal entanglement in uniform case. When the structure of the spin system are given, changing the external magnetic field B can induce controllable entanglement. Our study may provide a useful tool to change the entanglement of spin chain system. 相似文献
18.
A new model analysis of the third harmonic voltage in inductive measurement for critical current density of superconducting films 下载免费PDF全文
The critical current density J c is one of the most important parameters of high temperature superconducting films in superconducting applications,such as superconducting filter and superconducting Josephson devices.This paper presents a new model to describe inhomogeneous current distribution throughout the thickness of superconducting films applying magnetic field by solving the differential equation derived from Maxwell equation and the second London equation.Using this model,it accurately calculates the inductive third-harmonic voltage when the film applying magnetic field with the inductive measurement for J c.The theoretic curve is consistent with the experimental results about measuring superconducting film,especially when the third-harmonic voltage just exceeds zero.The J c value of superconducting films determined by the inductive method is also compared with results measured by four-probe transport method.The agreements between inductive method and transport method are very good. 相似文献
19.
We investigated the quantum entanglement in spin-1 Heisenberg XY chain for two-spin-qutrit and multi-particle systems. As a measure of the entanglement, the negativity of this state was
analyzed as a function of the temperature and the magnetic field. We gave some numerical results and discussed them in detail.
We found that the negativity increases monotonously with the coupling constants |J
1| and |J
2|, and it showed a symmetry with respect to the point of J
1 = 0 and J
2 = 0. In addition to the above features, there is evidence that the critical temperature is independent of the length of the
chain. 相似文献
20.
Xiu-Xing Zhang Xun-Chang Yin Guang-Hou Sun Chuan-Jia Shan 《International Journal of Theoretical Physics》2010,49(7):1507-1515
We investigate the pairwise thermal entanglement of the extended XY model with three spin interactions and external filed
on zig-zag lattice. The influences of three spin interactions J
2 and external field λ on the thermal entanglement of the nearest neighbor (NN) and next nearest neighbor (NNN) spins are considered. It is found
that J
2 and λ suppress both the maximal value and the critical temperature of the NN entanglement C
12. However, when it comes to the NNN entanglement C
13, there exists a critical value of J
2 above which both the maximal entanglement and the critical temperature can be enhanced by J
2 for a fixed external field. With J
2 fixed, the effect of λ on C
13 are different for different values of J
2. For J
2<1, λ suppresses both T
C
and the maximal values of C
13. For J
2≥1, λ enhances the maximal values of C
13 while decreases the critical temperature. These results show that one is able to get the entanglement wanted by properly
controlling the values of the three spin interactions J
2 and the external field λ. 相似文献