shown that the degree of entanglement exhibits damping oscillatory nature when there is no driving radiation where in between there is a narrow window of time in which the degree of entanglement is found to increase with the deviation of the phase fluctuation and rate of dephasing. The fluctuation of the degree of entanglement is solely attributed to the choice of the values of these parameters which are not completely independent.

Equations of evolution
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The interaction of a pumped nondegenerate three-level cascade atom with a resonant two-mode cavity radiation can be described in the rotating-wave approximation and the interaction picture by the Hamiltonian of the form $$\begin{aligned}
\label{p01}\hat{H} &=ig[\hat{a}|a\rangle\langle
b| - |b\rangle\langle a|\hat{a}^{\dagger} +\hat{b}|b\rangle\langle
c| - |c\rangle\langle b|\hat{b}^{\dagger}]\notag\\& +
i{\Omega\over2}[|c\rangle\langle a|-|a\rangle\langle c|],\end{aligned}$$ where $\Omega$ is a real-positive constant proportional to the amplitude of the driving radiation and $g$ is a coupling constant chosen to be the same for both transitions. $\hat{a}$ and $\hat{b}$ are the annihilation operators that represent the two cavity modes. In the cascade configuration, the transition from upper energy level $|a\rangle$ to the intermediate level $|b\rangle$ and from level $|b\rangle$ to the lower energy level $|c\rangle$ are taken to be resonant with the cavity radiation, whereas 