Wave-packet analysis of the quantum-confined Stark effect in coupled double quantum wells

The excitonic spectra and certain features of the quantum dynamics of electron-hole pairs in coupled double quantum wells under electrical bias are analyzed by a wave-packet propagation method. The excitonic system is described by a two-band model in the effective-mass envelope-wave-function approximation. The results describe the behavior of the bare pair distribution of electrons and holes under the Coulomb interaction and a longitudinal electric field (applied perpendicular to the wells). Many-body interaction, space-charge effects, and scattering by lattice and impurity mechanisms are not taken into account. The formalism is simplified by averaging out the in-plane motion of the electron-hole pairs using an appropriate 1s variational wave amplitude. An initial wave packet tailored to the absorption spectrum is propagated in real time using a split-step algorithm for the evolution operator and fast-Fourier-transform techniques. The quantum dynamics is recorded in the time dependence of the autocorrelation function linking the evolved and initial states, while the excitonic spectra are given by its Fourier transform. The variations of the wave-function overlap, mean particle positions, and phase-space volume are used as measures of quantum dynamics in the discussion. Results on the spectral and dynamic properties of the quantum-confined Stark effect are displayed separately for heavy holes and light holes.