Electromagnetically induced transparency and lasing without inversion in chiral molecules

Electromagnetically induced transparency and lasing without inversion are optical manifestations of quantum coherence control. Here we theoretically investigate these effects in a chiral molecule, coherently driven by an optical pump, finding that signal fields can undergo chiroptical absorption quenching or amplification within particular spectral windows at pump intensities as low as ≈ 1kW/cm 2 . Our calculations reveal that molecular chirality has the capacity to dramatically alter quantum coherence phenomena at peculiar wavelength ranges, modulating efficiently circular dichroism depending on the polarisation state of both pump and signal fields and the molecular orientation. We find that, for a given molecular orientation, the dissymmetry factor probed upon right/left-circular polarisation excitation by the signal can get maximised by pump polarisation tuning and the signal direction. By averaging over impinging signal orientations, we find that the orientation-averaged dissymmetry factor can diverge owing to electromagnetically induced transparency producing vanishing averaged absorption cross-sections.