Dynamics of quantum discord for a two-qubit system

郭有能, 方卯发, Xiang Liu +1 more

J. L. Guo, Yingjuan Mi, H. S. Song

王小云 黄勇刚

Lin Li, Jian Zou, Bao-Ming Xu +4 more

We investigate the influence of the initial correlations between a two-qubit system and a family of baths on the dynamics of quantum discord of these two qubits. We show that the initial states with entanglement between the two-qubit system and the bath can prompt two qubits to gain more quantum discord. Moreover, for the initial states only with discord but null entanglement between the two-qubit system and the bath, the effects depend on whether two qubits or one of the two qubits interact with the bath. We also find that there exist some specific initial states for which the entanglement between two qubits is invariant as time evolves, but the quantum discord is not, and for some other initial states although the states evolve, both the entanglement and the quantum discord remain invariant.

Ying-Jie Zhang, Xu‐Bo Zou, Yun‐Jie Xia +1 more

We analyze the roles of initial correlations between the two-qubit system and a dissipative cavity on quantum discord dynamics of two qubits. Considering two initial system-cavity states, we show that the initial system-cavity correlations not only can initially increase the two-qubit quantum discord but also would lead to a larger long-time quantum discord asymptotic value. Moreover, quantum discord due to initial correlations is more robust than the case of the initial factorized state. Finally, we show the initial correlations' importance for dynamics behaviors of mutual information and classical correlation.

You-neng Guo, Mao-Fa Fang, Xiang Liu +1 more

We study the quantum discord dynamics of two noninteracting qubits that are, respectively, subject to classical noise. The results show that the dynamics of quantum discord are dependent on both the coupling between the qubits and classical noise, and the average switching rate of the classical noise. In the weak-coupling Markovian region, quantum discord exhibits exponent decay without revival, and can be well protected by increasing the average classical noise switching rate. While in the strong-coupling non-Markovian region, quantum discord reveals slowly decayed oscillations with quick revival by decreasing the average switching rate of the classical noise. Thus, our results provide a new method of protecting quantum discord in a two-qubit system by controlling the coupling between the qubits and classical noise, and the average switching rate of the classical noise.