Rabi Flopping in a Two-Level System with a Time-Dependent Energy Renormalization: Intersubband Transitions in Quantum Wells

We obtain pulse-driven Rabi oscillations guided by a generalization of the rotating-wave approximation to include, in the optical-Bloch equations, two-level systems with a time-varying transition energy. We achieve this by using chirped pulses with the central frequency given by the time-varying transition energy. Using this approach, we predict Rabi oscillations in intersubband transitions in a two-subband $n$-type modulation-doped quantum well by taking into account the time-dependent intersubband energy-gap renormalization due to depolarization-shift effects. We obtain Rabi oscillations for $j\pi$ ($j=0,1,2,\dots$) pulses in the presence of dephasing.