Influence of the nonlinearity of nondegenerate parametric amplifier cavity fields on quantum phenomena of two coupled qubits

This paper studies the nonclassicality of a mixed qubit in the intrinsic decoherence model that describes the two dipole-coupled qubits interacting with a two-mode parametric amplifier cavity through four-photon transitions. After tracing the states of the cavity fields and one of the two qubits, we analyze some important quantum phenomena of the rested qubit, such as the phase space information, the mixedness via Husimi distribution and its associated Wehrl entropy, quantum Fisher information, and von Neumann entropy mixedness. These phenomena are sensitive to the two-qubit coupling and the intrinsic decoherence. Qubit–qubit interaction leads to enhancing the generated phase space information and the mixedness. The increase of the decoherence leads to erasing the phase space information of the rested qubit as well as increasing and stabilizing the generated qubit mixedness.