Complete quenching of fluorescence from a two-level atom driven by a weak,narrow-band, nonclassical light field

We consider a two-level atom driven by an ideal degenerate optical parametr ic oscillator. For squeezing bandwidths of the order of the natural width g amma, and smaller, we report remarkable spectral profiles for the scattered light. We also consider a system where the atom is driven by arbitrarily c orrelated light of arbitrary bandwidth. Employing analytic and numerical so lutions, we find different spectral features depending on the classical or nonclassical nature of the driving field. The spectral linewidth can be bot h subnatural and narrower than the incident field linewidth, an effect that does not require nonclassical light. However, nonclassical light is essent ial for the appearance of a narrow hole at line center. It is a unique sign ature of the quantum nature of the field, and for ideal squeezing, the fluo rescence at line center vanishes. [S1050-2947(99)50304-1].