Based on the calculation of all the pairwise entanglements in the n （n ≤ 6）-qubit Heisenberg XX open chain with system impurity, we find an important result： pairwise entanglement can only be transferred by an ent...Based on the calculation of all the pairwise entanglements in the n （n ≤ 6）-qubit Heisenberg XX open chain with system impurity, we find an important result： pairwise entanglement can only be transferred by an entangled pair. The non-nearest pairwise entanglements will have the possibility to exist as long as there has been even number of qubits in their middle. This point indicates that we can obtain longer distance entanglement in a solid system.展开更多
We calculate the concurrence of all pairwise entanglement of Heisenberg XX open chain with single systemimpurity in three-qubit and four-qubit cases,and find that the impurity parameter J_i has great effect on pairwis...We calculate the concurrence of all pairwise entanglement of Heisenberg XX open chain with single systemimpurity in three-qubit and four-qubit cases,and find that the impurity parameter J_i has great effect on pairwiseentanglement.Choosing the proper parameter J_i,we can obtain the maximal pairwise entanglement of the nearestqubits and make the non-nearest qubits entangle.展开更多
We investigate the behavior of geometric global quantum discord （GGQD） and concurrence （C） between half- spins of a mixed-three-spin （1/2, 1, 1/2） system with the Ising-XY model for which spins （1, 1/2） have t...We investigate the behavior of geometric global quantum discord （GGQD） and concurrence （C） between half- spins of a mixed-three-spin （1/2, 1, 1/2） system with the Ising-XY model for which spins （1, 1/2） have the Ising interaction and half-spins （1/2, 1/2） have both XY and the Dzyaloshinskii Moriya interactions together, under the decoherence action. A single-ion anisotropy property with coefficient ζ is assumed for the spin-integer. This system which includes an analytical Hamiltonian is considered at the front of an external homogeneous magnetic field B in thermal equilibrium. Finally, we compare GGQD and C and express some interesting phase flip reactions of the total quantum correlation and pairwise entanglement between spins （1/2, 1/2）. Generally, we conclude that the concurrence and GGQD have different behaviors under the phase flip channel.展开更多
The impurities of exchange couplings, external magnetic fields and Dzyaloshinskii-Moriya （DM） interaction considered as Gaussian distribution, and the entanglement in one-dimensional random XY spin systems is invest...The impurities of exchange couplings, external magnetic fields and Dzyaloshinskii-Moriya （DM） interaction considered as Gaussian distribution, and the entanglement in one-dimensional random XY spin systems is investigated by the method of solving the different spin-spin correlation functions and the average magnetization per spin. The entanglement dynamics at central locations of ferromagnetic and antiferromagnetic chains have been studied by varying the three impurities and the strength of DM interaction. （i） For the ferromagnetic spin chain, the weak DM interaction can improve the amount of entanglement to a large value, and the impurities have the opposite effect on the entanglement below and above critical DM interaction. （ii） For the antiferromagnetic spin chain, DM interaction can enhance the entanglement to a steady value. Our results imply that DM interaction strength, the impurity and exchange couplings （or magnetic field） play competing roles in enhancing quantum entanglement.展开更多
基金Project supported in part by the National Natural Science Foundation of China （Grant No 10547008）, and the Foundation of Xi＇an Institute of Posts and Telecommunications, China （Grant No 105-0414）.
文摘Based on the calculation of all the pairwise entanglements in the n （n ≤ 6）-qubit Heisenberg XX open chain with system impurity, we find an important result： pairwise entanglement can only be transferred by an entangled pair. The non-nearest pairwise entanglements will have the possibility to exist as long as there has been even number of qubits in their middle. This point indicates that we can obtain longer distance entanglement in a solid system.
基金The project supported by National Natural Science Foundation of China under Grant No.10547008the Foundation of Xi'an Institute of Posts and Telecommunications under Grant No. 105-0414Natural Science Fnundation of Shanxi Province under Grant No.2004A15
文摘We calculate the concurrence of all pairwise entanglement of Heisenberg XX open chain with single systemimpurity in three-qubit and four-qubit cases,and find that the impurity parameter J_i has great effect on pairwiseentanglement.Choosing the proper parameter J_i,we can obtain the maximal pairwise entanglement of the nearestqubits and make the non-nearest qubits entangle.
文摘We investigate the behavior of geometric global quantum discord （GGQD） and concurrence （C） between half- spins of a mixed-three-spin （1/2, 1, 1/2） system with the Ising-XY model for which spins （1, 1/2） have the Ising interaction and half-spins （1/2, 1/2） have both XY and the Dzyaloshinskii Moriya interactions together, under the decoherence action. A single-ion anisotropy property with coefficient ζ is assumed for the spin-integer. This system which includes an analytical Hamiltonian is considered at the front of an external homogeneous magnetic field B in thermal equilibrium. Finally, we compare GGQD and C and express some interesting phase flip reactions of the total quantum correlation and pairwise entanglement between spins （1/2, 1/2）. Generally, we conclude that the concurrence and GGQD have different behaviors under the phase flip channel.
基金Supported by the Key Higher Education Programme of Hubei Province under Grant No Z20052201, the Natural Science Foundation of Hubei Province, China under Grant No 2006ABA055, and the Postgraduate Programme of Hubei Normal University under Grant No 2007D20.
文摘The impurities of exchange couplings, external magnetic fields and Dzyaloshinskii-Moriya （DM） interaction considered as Gaussian distribution, and the entanglement in one-dimensional random XY spin systems is investigated by the method of solving the different spin-spin correlation functions and the average magnetization per spin. The entanglement dynamics at central locations of ferromagnetic and antiferromagnetic chains have been studied by varying the three impurities and the strength of DM interaction. （i） For the ferromagnetic spin chain, the weak DM interaction can improve the amount of entanglement to a large value, and the impurities have the opposite effect on the entanglement below and above critical DM interaction. （ii） For the antiferromagnetic spin chain, DM interaction can enhance the entanglement to a steady value. Our results imply that DM interaction strength, the impurity and exchange couplings （or magnetic field） play competing roles in enhancing quantum entanglement.
