Effects of a high nonlinear interaction between an open parametric amplifier cavity and a qubit on dynamics of the correlation function and quantum Fisher information

In this paper, we provide an analytical description of the intrinsic noise model of the two-mode cavity, containing a single two-level atom through su(1,1)-algebraic treatment. Each field interacts with the qubit through a four-photon process and is assumed initially in Barut-Girardello coherent state. The Atomic Quantum Fisher information (AQFI), atomic entropy and the correlation function are analyzed under the effects of the intrinsic damping and the superposition of the initial generalized Barut-Girardello Coherent States (B-GCS). Under the nonlinear interactions, the AQFI has irregular oscillatory behavior that depends on the superposition of the B-GCS. Due to the high nonlinear interactions, the damping work with a very small value and leads to the degradation of the AQFI. This degradation can be enhanced in the case of the even B-GCS. The generated entanglement and mixedness of the atomic entropy are explored, they are very sensitive to the physical parameters of the intrinsic damping, the detuning and the initial cavity state. It is found that the second-order correlation depends on the mean photon number, the superposition of the B-GCS, and the damping. For the small value of the mean photon number and with the damping, the sub-Poissonian effects increase with the B-GCS, while the super-Poissonian behavior increases with its even states. For the off-resonant case, the frequency, the regularity and stability of the NSOC function, the atomic entropy and the AQFI are enhanced. •Entanglement and mixture in parametric amplifier cavity contained two qubits.•Dynamics of the von Neumann.•Dynamics of the Fisher information.•The generate of mixedness, cavity-qubit/qubit-qubit entanglements.