Broadband EM radiation amplification by means of a monochromatically driven two-level system
Andrey Vladimirovich Soldatov · Modern Physics Letters B · 2017
It is shown that a two-level quantum system possessing dipole moment operator with permanent non-equal diagonal matrix elements and driven by external semiclassical monochromatic high-frequency electromagnetic (EM) (laser) field can amplify EM radiation waves of much lower frequency.