Decoherence of a two-qubit system interacting with initially correlated random telegraph noises

Abstract

Decoherence of a two-qubit system is studied in terms of an exactly solvable dephasing model. In this model, the two qubits are influenced by the random telegraph noises (RTNs) which are dynamically independent but initially correlated, where the initial correlation means that joint probability of the two RTNs is not factorizable at an initial time. It is shown that the purely classical initial correlation between the RTNs can create interesting effects on the time evolution of the two-qubit system. For this purpose, two-qubit coherence, entanglement and other correlations are investigated in detail. It is found that the initial correlation can suppress the decoherence of the two-qubit system. The most important result is that the time evolution of the two-qubit system can become non-Markovian in the presence of the initial correlation, even if it is Markovian in the absence of the initial correlation. Furthermore, it is shown that the initial correlation between the RTNs can enhance quantum coherence and correlation of the two-qubit system.