We show that quantum-interference-related phenomena, such as electromagnetically induced transparency, gain without inversion and enhanced refractive index may occur on electric-dipole forbidden transitions. Gain/dispersion characteristics of such tr
ansitions strongly depend upon the relative phase between the driving and probe fields. Unlike allowed transitions, gain/absorption behavior of forbidden transitions exhibit antisymmetric feature on the Rabi sidebands. Absorption/gain spectra possess extremely narrow sub-natural resonances.
