Coherently driven two-level atom in open space and interacting with vacuum modes

In this paper, we consider a coherently driven two-level atom in open space and interacting with vacuum reservoir. Using the master equation and the interaction Hamiltonian, we obtain the time evolution of the expectation values of the atomic operators. Applying the large time approximation scheme on these equation, we determined the solution of the expectation values of the atomic operators. With the aid of the resulting solution, we study the power spectrum, the atomic inversion, the mean photon number, and the normalised second-order correlation function of the fluorescent light in the weak and strong driving light limits. Moreover, we have found that the probability for the atom to be in the upper level.