Quantum correlations dynamics and decoherence of a three-qubit system subject to classical environmental noise

Dynamics of entanglement and state-space trajectories followed by a system of four-qubit in the presence of random telegraph noise: common environment (CE) versus independent environments (IEs)

“…Overall, having compared the results obtained in this subsection with those obtained in the previous one, we find that the amount of entanglement initially present in the four-qubit GHZ-type states is more robustly shielded from decoherence than that of the four-qubit W-type states when the qubits are embedded in a common environment. This is in agreement with what was previously found in the three-qubit form of the model studied in the present paper [57,58,73]. Besides, unlike GHZ-type states in which the CE coupling always preserves more entanglement than the IEs coupling, we find that for W-type states, the IEs and CE coupling may play opposite roles in the preservation of entanglement among the qubits, depending upon the purity q and the period of time considered.…”

Decoherence and protection of entanglement of a system of three qubits driven by a classical Gaussian distributed fluctuating field

“…It is important to note that the same evolution operator can be obtained without any approximation but rather in the situation were the energy levels of the qubit are degenerated as in Refs. [17,19,22]. In other words, we show that when a qubit is couple to a CSF having a spectrum with frequencies that are larger than its natural frequency, its dynamics is approximately the same as the one of a qubit with degenerated energy levels coupled to the same CSF.…”

“…Such a result is in good agreement with what has been found in Refs. [19,22]. However, the opposite situation occurs when the qubits are initially set in the W state, that is, when the qubits are prepared in the W state, the CE configuration followed by MEs one hastens the disentanglement of the qubits than the IEs setup.…”

“…In recent year, the dynamics of quantum correlations in the situation where quantum systems are affected by environments describes classically (i.e., model by means of a classical Gaussian or non-Gaussian distributed random field) has been an active area of research [6,7,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] and many interesting results have been obtained. In particular, it has been shown that when three qubits are coupled to an external classical noise such as random telegraph noise [16][17][18], static noise [20] and colored noise [19,21] in a common environment, quantum correlations among them survive indefinitely. However, it is worth noting that the majority of these works deals with bipartite systems.…”

“…In this paper, we consider a system of three non-interacting qubits coupled with an external classical environment in three different scenarios namely: common, independent and mixed environment(s) (see figure 1 of Refs. [19,20]). In the first scenario, we assume that the three qubits are coupled to the same environment; in the second scenario, we assume that each qubit is coupled to its own environment while in the third scenario two of them are coupled to the same environment and the remaining one to its own environment.…”