Nonlinear Channels of Werner States

Ma-Cheng Yang, Jun-Li Li, Cong-Feng Qiao

Vladimir I. Man’ko, Roman S. Puzko

The nonlinear positive map of density matrix of two-qubit Werner state called nonlinear channel is studied. The map of density matrix is realized by rational function. The influence of the map onto the entanglement properties of the transformed density matrix is discussed. The violation of Bell inequality (CHSH inequality) for the two-qubit state is investigated. The nonlinear channels under discussion create the entangled state from separable Werner state. The quantum spin-tomograms of the states are studied.

Nan Li, Shunlong Luo, Yuan Sun

Vladimir I. Man’ko, Roman S. Puzko

The entropic and information inequalities for two qubit X-states transformed by the nonlinear channels are given in explicit form. The subadditivity condition and nonnegativity of von Neumann quantum information are studied for both initial X-state and the state after action of the nonlinear channel. Partial case of Werner state is considered in detail. We shown that the von Neumann information increases due to action of the nonlinear channel. We generalize the results obtained for Werner state in our earlier article [J. Russ. Laser Res., \textbf{35}, iss. 3 (2014)] to the case of X-state of two qubit system. We study the influence of nonlinear channel acting on X-state of two qubit system onto von Neumann mutual information.

Liao Qing-hon

We investigated the entanglement properties of Werner state through the noisy quantum channels(including amplitude and phase damping channels)by employing the concurrence.We derived the analytical expression of concurrence for Werner state under the noisy quantum channels.The condition for sudden death of entanglement was obtained.

王胜房, 刘益民, 李国锋 +2 more