Phase-conjugated mirror-induced oscillations outside the rotating-wave approximation

Dynamical behaviour of a single harmonic oscillator (HO) and of a single and two cooperative atoms in front of a phase-conjugated mirror is , investigated without using the rotating-wave approximation. The mean photon number of the HO shows transient oscillation of frequency (2omega(o)) and O(gamma/omega(o)), the ratio of the free-space decay rate to the oscillation frequency, and the fluorescent spectrum becomes asymmetric due to additional resonant and non-resonant dispersive terms. In the single-two-level-atom case, the mean atomic inversion and the fluorescent intensity show steady oscillation O(gamma(o)/omega(o)), the ratio of the A-coefficient to the atomic transition frequency. The amplitude of this steady oscillation at frequency (2omega(o)) is larger in the case of two cooperative atoms.