Dynamics of bipartite quantum correlations and coherence in classical environments described by pure and mixed Gaussian noises

Abstract

We discuss the time evolution of entanglement, purity, and coherence of two non-interacting maximally entangled qubits in two different classical environmental configurations: bipartite and independent system–environment configuration. Gaussian noises, such as fractional Gaussian $(\mathcal {F_G})$ and power-law ($\mathcal {P_L})$ noise, are considered characterizing these environments. In particular, we are interested in exploring the dephasing effects in two qubits caused by the Gaussian noises in pure and mixed situations using entanglement witness, concurrence, purity, and decoherence measures. We notice both the noises in pure and in mixed forms are highly dephasing, and the bipartite quantum correlation, purity, and coherence eventually disappear after a finite interaction time. We notice that the current quantum phenomena decay faster under $\mathcal {F_G}$ noise than under $\mathcal {P_L}$ noise. Also, in independent system–environment configuration, the bipartite state is found to have slightly longer quantum correlation, purity, and coherence preservation than common environments, suggesting it more favourable for such quantum operations. For increasing values of the memory parameter of the $\mathcal {F_G}$ noise, the entanglement, purity, and coherence become initially robust, defying the dephasing character of parameters of nearly all the noises. The wide spectrum of the pure $\mathcal {P_L}$ noise can be readily exploited to design long preservation effects, especially by fixing the noise parameters to utmost low values. Also, the decay outlook induced by both noises is a monotonous function of time, with no entanglement sudden death and births observed.