Chinese Physics B

Jia-Qi, Mo; Wan-Tao, Lin

doi: 10.1088/1674-1056/17/3/001pmid: N/A

The EI Niño and Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific seaair interactions. In this paper, an asymptotic method of solving nonlinear equations for the ENSO model is proposed. And based on a class of oscillator of the ENSO model and by employing the method of homotopic mapping, the approximate solution of equations for the corresponding ENSO model is studied. It is proved from the results that homotopic method can be used for analysing the sea surface temperature anomaly in the equatorial Pacific of the seaair oscillator for the ENSO model.

Jin-Hua, Li; Sen-Yue, Lou

doi: 10.1088/1674-1056/17/3/002pmid: N/A

Based on some known facts of integrable models, this paper proposes a new (2+1)-dimensional bilinear model equation. By virtue of the formal series symmetry approach, the new model is proved to be integrable because of the existence of the higher order symmetries. The Lie point symmetries of the model constitute an infinite dimensional KacMoodyVirasoro symmetry algebra. Making use of the infinite Lie point symmetries, the possible symmetry reductions of the model are also studied.

Shen-Yang, Shi; Jing-Li, Fu; Xiao-Hong, Huang; Li-Qun, Chen; Xiao-Bo, Zhang

doi: 10.1088/1674-1056/17/3/003pmid: N/A

This paper studies the Lie symmetries and Noether conserved quantities of discrete mechanical systems with variable mass. The discrete EulerLagrange equation and energy evolution equation are derived by using a total variational principle. The invariance of discrete equations under infinitesimal transformation groups is defined to be Lie symmetry. The condition of obtaining the Noether conserved quantities from the Lie symmetries is also presented. An example is discussed for applications of the results.

Hua-Mei, Li

doi: 10.1088/1674-1056/17/3/004pmid: N/A

This paper analyses bright and dark spatial self-similar waves propagation and collision in graded-index nonlinear waveguide amplifiers with self-focusing and self-defocusing Kerr nonlinearities. It finds an appropriate transformation for the first time such that the nonlinear Schrödinger equation (NLSE) with varying coefficients transform into standard NLSE. It obtains one-solitonlike, two-solitonlike and multi-solitonlike self-similar wave solutions by using the transformation. Furthermore, it analyses the features of the self-similar waves and their collisions.

Ai-Xia, Mu; Xiao-Yan, Zhou; Ju-Kui, Xue

doi: 10.1088/1674-1056/17/3/005pmid: N/A

In this paper, we consider the macroscopic quantum tunnelling and self-trapping phenomena of BoseEinstein condensates (BECs) with three-body recombination losses and atoms feeding from thermal cloud in triple-well potential. Using the three-mode approximation, three coupled GrossPitaevskii equations (GPEs), which describe the dynamics of the system, are obtained. The corresponding numerical results reveal some interesting characteristics of BECs for different scattering lengths. The self-trapping and quantum tunnelling both are found in zero-phase and -phase modes. Furthermore, we observe the quantum beating phenomenon and the resonance character during the self-trapping and quantum tunnelling. It is also shown that the initial phase has a significant effect on the dynamics of the system.

Xiu-Bo, Chen; Jian-Zhong, Du; Qiao-Yan, Wen; Fu-Chen, Zhu

doi: 10.1088/1674-1056/17/3/006pmid: N/A

Utilizing the generalized measurement described by positive operator-valued measure, this paper comes up with a protocol for teleportation of an unknown multi-particle entangled (GHZ) state with a certain probability. The feature of the present protocol is to weaken requirement for the quantum channel initially shared by sender and receiver. All unitary transformations performed by receiver are summarized into a formula. On the other hand, this paper explicitly constructs the efficient quantum circuits for implementing the proposed teleportation by means of universal quantum logic operations in quantum computation.

Li-Bing, Chen; Rui-Bo, Jin; Hong, Lu

doi: 10.1088/1674-1056/17/3/007pmid: N/A

Remote quantum-state discrimination is a critical step for the implementation of quantum communication network and distributed quantum computation. We present a protocol for remotely implementing the unambiguous discrimination between nonorthogonal states using quantum entanglements, local operations, and classical communications. This protocol consists of a remote generalized measurement described by a positive operator valued measurement (POVM). We explicitly construct the required remote POVM. The remote POVM can be realized by performing a nonlocal controlled-rotation operation on two spatially separated qubits, one is an ancillary qubit and the other is the qubit which is encoded by two nonorthogonal states to be distinguished, and a conventional local Von Neumann orthogonal measurement on the ancilla. The particular pair of states that can be remotely and unambiguously distinguished is specified by the state of the ancilla. The probability of successful discrimination is not optimal for all admissible pairs. However, for some subset it can be very close to an optimal value in an ordinary local POVM.

Jin, Zhang

doi: 10.1088/1674-1056/17/3/008pmid: N/A

We propose feasible schemes for preparation of all five-atom graph states by cavity quantum electrodynamics (QED). Our schemes require only the atomcavity interaction with a large detuning which is available in current experiment so that these schemes are within the reach of the current technology.

Ying-Jie, Zhang; Ting-Qi, Ren; Yun-Jie, Xia

doi: 10.1088/1674-1056/17/3/009pmid: N/A

By using the theory of cavity QED, we study the system in which a two-level atom interacts with a cavity in the case of large detuning. Through the selective detecting of atomic state, Schrödinger cat states and entangled coherent states are easily generated. When the atom is driven by a weak classical field and the cavity field is in the Schrödinger cat state, we study the conditions of generating the Fock states and the maximal success probability. The maximal success probability in our scheme is larger than the previous one.

Chuan-Jia, Shan; Wei-Wen, Cheng; Tang-Kun, Liu; Yan-Xia, Huang; Hong, Li; Yun-Jie, Xia

doi: 10.1088/1674-1056/17/3/010pmid: N/A

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 spinspin 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.