Coherent control of quantum states by single frequency-chirped laser pulses and electromagnetically self-induced transparency

This paper shows that a single laser pulse with a chirped frequency can generate trapped superposition of the ground states in the Λ-atom when the width of the transform-limited laser pulse envelope frequency spectrum (without chirp) is smaller but the peak Rabi frequency of the pulse is larger than frequency interval between the two ground states of the Λ-atom. This study also analyzes the propagation of the frequency-chirped laser pulse in a medium consisting of Λ-atoms analytically and by exact numerical solution of coupled Bloch-Maxwell equations. The results show that there is nearly absorptionless propagation of the single frequency-chirped laser pulse on distances more than 40 times the pulse duration, when the formulated above conditions of negligible excitation of the Λ-atom are fulfilled. The described effect of absorptionless propagation of the single frequency-chirped pulse is referred to as electromagnetically self-induced transparency.