Quantum interference in a four-level system of a ⁸⁷Rb atom: Effects of spontaneously generated coherence

In this work, the effects of quantum interference and spontaneously generated coherence (SGC) are theoretically analyzed in a four level system of a $^{87}\mathrm{Rb}$ atom. For the effects of SGC, we find that a new kind of EIT channel can be induced due to destructive interference, and the nonlinear Kerr absorption can be coherently narrowed or eliminated under different strengths of the coupling and switching fields.