Absorptive central line-shapes of a driven atom in a squeezed reservoir

Amplification of absorption spectrum of a weak signal probing the system of a dissipative single 2-level atom in the presence of a broadband squeezed vacuum (SV) reservoir and driven by a non-resonant mono- or bi-chromatic coherent field is investigated. The non-autonomous model Bloch equations yields solutions for the atomic variables of all harmonic frequency components, exp(±inνt); n=0, 1, … where ν is the probe frequency detuning. Amplification of the fundamental (n=0) and the first harmonic (n=1) frequency components associated with the central part (|ν|