Suppression of absorption by quantum interference in intersubband   transitions of tunnel-coupled double quantum wells
  We propose and analyze an efficient scheme for suppressing the absorption of a weak probe field based on intersubband transitions in a four-level asymmetric coupled-quantum well (CQW) driven coherently by a probe laser field and a control laser field. By using the numerical simulation, we find that the magnitude of the transient absorption of the probe field is smaller than the three-level system based on the electromagnetically induced transparency (EIT) at line center of the probe transition, moreover, comparing with the scheme in three-level asymmetric double QW system, the transparency hole of the present work is much broader. By analyzing the steady-state process analytically and numerically, our results show that the probe absorption can be completely eliminated under the condition of Raman resonance (i.e. two-photon detuning is zero). Besides, we can observe one transparency window without requiring one- or two-photon detuning exactly vanish. This investigation may provide the possible scheme for EIT in solids by using CQW. 
Wen-Xing Yang, Jin Xu, and Ray-Kuang Lee