Far-infrared-driven electron-hole correlations in a quantum dot with an internal tunneling barrier - art. no. 155322

Laser excited and FIR-driven, time-dependent electron-hole correlations in a prototypical GaAs quantum dot with an internal AlGaAs tunneling barrier a re studied by numerical propagation of the time-dependent Schrodinger equat ion. The dimensions of the dot are 13 x 25 x 25 nm(3) (denoted x, y, and z directions, respectively). The width of the symmetrically placed barrier in the x direction varies between 1 and 4 nm. The simulations, including a sc reened Coulomb interaction, time-propagates the electron-hole (exciton) wav e function within the effective mass approximation. The Coulomb correlation s are treated within the time-dependent configuration-interaction method, T he hole mass is chosen to be heavy along the growth direction (x) and light in the lateral directions. The presence of the barrier allows the energy s plittings of the excited states to be tuned for optimal correlation effects . Three cases illustrate how sequences of NIR and FIR pulses can excite and probe coherent correlation effects. Case I: A single FIR-coupled dark eige nstate can be used to modulate correlation induced beatings in a pair of op tically excited eigenstates, but the beating is not significantly transferr ed into the dark state. Case II: With appropriate FIR pulse widths and cent er frequencies, a coherent optical excitation in a pair of correlation spli t states can be transferred unchanged into and out of a pair of optically d ark states split by similar correlations. Case III: Correlations open new o ptical pathways that, for example, allow FIR pulses polarized in the x dire ction to transfer an excitonic excitation in x to an excitation in the perp endicular y and z directions.