Liang Qiu

Relating tripartite quantum discord with multisite entanglement and their performance in the one-dimensional anisotropic XXZ model

In order to define quantum correlations, there are two important paradigms in quantum information theory, viz. the information-theoretic and the entanglement-separability ones. In this paper, we give an analytical relation between two measures of quantum correlations. One of them is related to the monogamy of squared bipartite quantum discord, which is a information-theoretic multipartite quantum correlation measure, while the other is the generalized geometric measure which lies in the entanglement-separability paradigm. We find a certain cone-like region on the two-dimensional spaces spanned by the two measures. Moreover, we have investigated the quantum phase transition with the two measures in the anisotropic spin XXZ model by exploiting the quantum renormalization group method.

Entanglement sudden death in a spin channel

We study the dynamic evolution of the entanglement in a spin channel with an XY-type interaction initially in an entangled state. We find that the phenomenon of entanglement sudden death (ESD) appears in the evolution of entanglement for some initial states. We calculate the entanglement and obtain the parameter regions of disentanglement for the chains with several numbers of sites. The influence of the presence of one common spin environment is also discussed.

Effect of Dzyaloshinskii–Moriya anisotropic antisymmetric interaction on optimal dense coding

We study optimal dense coding in the two-qubit and two-qutrit Heisenberg XXX models with Dzyaloshinskii–Moriya anisotropic antisymmetric interaction (DM interaction). Both the DM interaction and the coupling parameter can enhance the maximum dense coding capacity for high temperature. For low temperature, in the two-qutrit system, the coupling parameter still enhances the maximum dense coding capacity, while the DM interaction weakens the capacity of the channel for dense coding.