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Using the three criterions of the concurrence, the negative eigenvalue and the geometric quantum discord, we investigate the quantum entanglement and quantum correlation dynamics of two two-level atoms interacting with the coherent state optical field. We discuss the influence of different photon number of the mean square fluctuations on the temporal evolution of the concurrence, the negative eigenvalue and the geometric quantum discord between two atoms when the two atoms are initially in specific three states. The results show that different photon number of the mean square fluctuations can lead to different effects of quantum entanglement and quantum correlation dynamics. [ABSTRACT FROM AUTHOR]

Quantum correlations of two atoms in a system of two entangled atoms interacting with the binomial optical field are investigated. In eight different initial states of the two atoms, the influence of the strength of the dipole-dipole interaction, probabilities of a the Bernoulli trial and particle number of the binomial optical field on the temporal evolution of the geometrical quantum discord between two atoms are discussed. The result shows that two atoms always exist the correlation for different parameters. In addition, when and only when the two atoms are initially in the maximally entangled state, the temporal evolution of geometrical quantum discord is not affected by the parameters, and always keep in the degree of geometrical quantum discord that is a fixed value. [ABSTRACT FROM AUTHOR]

Using the Pegg–Barnett formalism of phase operator, we obtain phase probability distributions of new even and odd nonlinear coherent states. It is shown that the distributions for the states are rather different, and unlike the case of ordinary even and odd coherent states the Pegg–Barnett distribution clearly reflects the different character of quantum interference in the case of the new even and odd coherent states. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the entanglement properties of entangled coherentstate in symmetrical phase space interacting with entangled atoms. Using the numerical calculations we discussed the entanglement between entangled atoms and entangled coherent field by the means of the von Neumann entropy, and the entanglement of the two atoms by the means of the negative eigenvalues of the partial transposition of reduced density matrix. The result shows that the strength of the light field, the relative phase factor have visibly influence on the degree of the entanglement. The impact on the entanglement by the coherent argument is tiny obvious. [ABSTRACT FROM AUTHOR]

By the methods of Jordan-Wigner transformation and Bogolyubov transformation, in this paper, we diagonalized the Hamiltonian in one-dimensional Heisenberg spin chain model with Dzyaloshinskii-Moriya interactions and three-body interactions, and further analyze the effect of the Dzyaloshinskii-Moriya interaction and different three-body interactions on the Bogolyubov transformation and the energy spectrum of quantum spin chains. The results shows that only the energy spectrum but not the coefficients of the Bogolyubov transformation depends on DM interaction and one type of three-site exchange interaction. Another kind of three-body interaction not only can move the criticality region, but also can generate a new critical point. [ABSTRACT FROM AUTHOR]

In this paper, we proposed an experimentally feasible new scheme for controlled quantum secure direct communication in cavity quantum electrodynamics without apparent joint Bell-state measurement. According to the results measured by the sender and the controller, the receiver can obtain different secret messages in a deterministic way using GHZ state as the quantum channel with unit successful probability if controller cooperates with it. In the communication processes, with the assistance of a strong classical driving field, the interactions between atoms and a single-mode nonresonant cavity substitute the generalized joint Bell-basis measurements. So this scheme only need separate measurements. In addition, the scheme is insensitive to the cavity decay and the thermal field. The discussion of the scheme indicates that it is simple and realizable with present technology. [ABSTRACT FROM AUTHOR]