Pulse-driven interwell carrier transfer in n-type doped asymmetric double quantum wells

摘要

We use chirped pulses to achieve substantial electron population transfer from the wider well to the narrower well of an n-type doped asymmetric double quantum well (QW). To realize this goal we are guided by a generalization of the rotating-wave approximation to include, in the optical-Bloch equations for three-subband QW's, a time-varying central frequency equal to the renormalized intersubband transition energy. The energy-gap renormalization in our model is due to depolarization-shift effects. The first pulse central frequency is near the time-varying renormalized ∈_2-∈_0 gap, while the second pulse is near the renormalized ∈_2-∈_1 gap. An upper-bound estimate of the Hartree-Fock corrections to these transition energies is given. We find out that for the QW structure and the sheet density used these corrections are small.