Nonclassicality in a dispersive atom-cavity field interaction in presence of an external driving field

Abstract: We investigate nonclassical properties of a state generated by the interaction of a three-level atom with a quantized cavity field and an external classical driving field. In this study, the fields being degenerate in frequency, are highly detuned from the atom. The atom interacts with the quantized field in a dispersive manner. The experimental set-up involves a three-level atom passing through a cavity and interacting dispersively with the cavity field mode. Simultaneously, the atom interacts with an external classical field that is in resonance with the cavity field. The three-level atom can enter the cavity in one of the bare states $\ket{e}$, $\ket{f}$ or $\ket{g}$ or in a superposition of two of these states. In this paper, we consider superposition of $\ket{e}$ and $\ket{f}$. In our analysis, we focus on the statistical properties of the cavity field after interacting with the atom. The state vector $|\psi(t)\rangle$ describes the entire atom-field system but we analyze the properties of the cavity field independently neglecting the atomic component of the system. For this the atom part is traced out from $|\psi(t)\rangle$ to acquire the cavity field state only, denoted by $\ket{\psi_{ f}(t)}$. We evaluate different nonclassical measures including photon number distribution, Mandel's $Q_M$ parameter, squeezing properties $S_x$ and $S_p$, Wigner distribution, $Q_f$ function, second-order correlation function $g^2(0)$ etc. for the obtained cavity field state.