Coherent control of ac Stark allowed transition in $\Lambda$ system

TL;DR

This paper demonstrates that quantum interference effects like EIT and gain without inversion can occur on electric-dipole forbidden transitions, with unique phase-dependent and antisymmetric spectral features.

Contribution

It reveals the possibility of controlling forbidden transitions using quantum interference, expanding the scope of coherent optical phenomena beyond allowed transitions.

Findings

Forbidden transitions exhibit phase-dependent gain and absorption.

Spectra show extremely narrow sub-natural resonances.

Antisymmetric gain/absorption features on Rabi sidebands.

Abstract

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 transitions 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.