Effects of classical random external field on the dynamics of entanglement in a four-qubit system

We investigate the dynamics of entanglement through negativity and witness operators in a system of four non-interacting qubits driven by a classical phase noisy laser characterized by a classical random external field (CREF). The qubits are initially prepared in the GHZ-type and W-type states and interact with the CREF in two different qubit-field configurations, namely, common environment and independent environments in which the cases of equal and different field phase probabilities are distinguished. We find that entanglement exhibits different decaying behavior, depending on the input states of the qubits, the qubit-field coupling configuration, and field phase probabilities. On the one hand, we demonstrate that the coupling of the qubits in a common environment is an alternative and more efficient strategy to completely shield the system from the detrimental impacts of the decoherence process induced by a CREF, independent of the input state and the field phase probabilities considered. Also, we show that GHZ-type states have strong dynamics under CREF as compared to W-type states. On the other hand, we demonstrate that in the model investigated the system robustness's can be greatly improved by increasing the number of qubits constituting the system.

Automated summary

In this study, the dynamics of entanglement in a system of four non-interacting qubits driven by a classical phase noisy laser characterized by a classical random external field (CREF) were investigated. It was found that coupling qubits in a common environment is an effective strategy to shield the system from the detrimental impacts of decoherence induced by CREF, and GHZ-type states exhibit stronger dynamics compared to W-type states under CREF. Additionally, system robustness can be greatly improved by increasing the number of qubits in the system.