A Disentanglement Scheme of One-off on Two Einstein-Podolsky-Rosen Pairs of Atoms

Along with the rapid development of the field of quantum information, quantum entanglement plays key roles in quantum information processing. The well-known Einstein-Podolsky-Rosen state proposed in Ref[1].     

一种新的奇偶非线性相干态及其量子统计性质

定义了一种新的奇偶非线性相干态即算符B2[B=af(N)]的两个正交归一本征态,利用数值计算方法研究了它们的量子统计性质.结果表明,与通常的奇偶相干态不同,在参数|β|变化的某些范围内,只有偶非线性相干态可以存在压缩效应,而振幅平方压缩和反聚束效应在这两个态中均可以呈现 关键词： 新的奇偶非线性相干态 压缩 振幅平方压缩 反聚束效应     

两量子位原子与二项式光场相互作用的几何量子失协

研究了任意两量子位原子与二项式光场相互作用系统中两原子间的量子关联,讨论了特定的三种原子初态下的不同参数的二项式光场对几何量子失协随时间演化的影响。结果表明:二项式光场的光子数M和概率σ对几何量子失协演化曲线有明显的影响。不同原子初态下,几何量子失协演化曲线的振幅、相位和周期性表现出不同的特点。     

Entanglement control in one-dimensional s= 1/2 random XY spin chain

The entanglement in one-dimensional random XY spin systems where the impurities of exchange couplings and the external magnetic fields are considered as random variables is investigated by solving the different spin-spin correlation functions and the average magnetization per spin. The entanglement dynamics near particular locations of the system is also studied when the exchange couplings （or the external magnetic fields） satisfy three different distributions （the Gaussian distribution, double-Gaussian distribution, and bimodal distribution）. We find that the entanglement can be controlled by varying the strength of external magnetic field and the distributions of impurities. Moreover, the entanglement of some nearest-neighbouring qubits can be increased for certain parameter values of the three different distributions.     

Entanglement in One-Dimensional Random XY Spin Chain with Dzyaloshinskii--Moriya Interaction

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.     

Entanglement and quantum phase transition in alternating XY spin chain with next-nearest neighbouring interactions

By using the method of density-matrix renormalization-group to solve the different spin spin correlation functions, the nearest-neighbouring entanglement （NNE） and the next-nearest-neighbouring entanglement （NNNE） of one-dimensional alternating Heisenberg XY spin chain are investigated in the presence of alternating the-nearestneighbouring interaction of exchange couplings, external magnetic fields and the next-nearest neighbouring interaction. For a dimerised ferromagnetic spin chain, the NNNE appears only above a critical dimerized interaction, meanwhile, the dimerized interaction a effects a quantum phase transition point and improves the NNNE to a large extent. We also study the effect of ferromagnetic or antiferromagnetic next-nearest neighbouring （NNN） interaction on the dynamics of NNE and NNNE. The ferromagnetic NNN interaction increases and shrinks the NNE below and above a critical frustrated interaction respectively, while the antiferromagnetic NNN interaction always reduces the NNE. The antiferromagnetic NNN interaction results in a large value of NNNE compared with the case where the NNN interaction is ferromagnetic.     

Q变形非简谐振子广义奇偶相干态的高阶压缩特性

给出了Q变形的非简谐振子广义奇偶相干态的完备性证明,并且研究了它们的高阶压缩特性.结果表明,它们可组成一个完备的Hilbert空间,且均可呈现奇数阶压缩效应.     

算符(f(“非汉字符号”))k正交归一本征态的非经典特性

证明了算符(a^f(n^))k(k≥3)的k个正交归一本征态的完备性,引入了反聚束效应和一种新的高阶压缩,研究了算符(a^f(n^))k的k个本征态的反聚束效应和高阶压缩特性.结果表明,这些态可以构成一个完备的希尔伯特(Hilbert)空间,它们均可呈现反聚束效应,且当k为偶数时它们可呈现M阶[M=(n+12)k;n=0,1,2,…]压缩效应 关键词： 算符(a^f(n^))k的本征态 完备性 反聚束效应 高阶压缩     

Entanglement Swapping and Disentanglement via an Entangled State of Atoms Interacting with a Cavity Field

We consider entanglement swapping and disentanglement schemes via an entangled state of three two-level atoms interacting with a coherent field.When a two-level atom C,entangled with two other two-level atoms A and B,is injected into a high-Q cavity and atoms A and B are far away from the cavity,the entanglement swapping or disentanglement can be realized by carrying out the measurement on the atom C and by selecting an appropriate interaction time of atom C with the coherent field.