Fidelity of quantum states in a correlated dephasing channel

The effects of classical correlations and associated decoherence on the fidelity dynamics of two qubits initially prepared in maximally entangled (ME) and coherent states are examined. In both the Markovian and non-Markovian regimes, the dynamics of fidelity in a correlated dephasing channel is probed. We show that fidelity decreases over time but does not disappear completely, implying that the output state does not become quite dissimilar from the input state under the effects of dephasing correlated channel. The ME state, in comparison, is more tolerant of the dephasing effects of the correlated channel than that of the maximally coherent state. Fidelity of the quantum states is significantly influenced by the degree of classical correlations between successive actions of the channel on the two qubits. As the amount of classical correlations in the implementation of the channel increases, the fidelity of the quantum states can be noticeably enhanced.