A PHOTON ASSEMBLY-LINE ON A SEMICONDUCTOR QUANTUM-WELL

The lateral potential superlattice accompanying a surface acoustic wav e on a semiconductor quantum well structure is employed to efficiently transform light into a long-lived electron-hole polarization that can be reassembled into photons after very long storage times. Both the l ocation of the emission process on the sample and the storage-time can be chosen at will as the dynamical superlattice is able to transport the photogenerated excitations over macroscopic distances across the s emiconductor sample. The ionization process of the photogenerated exci tons in the piezoelectric fields of the sound wave can be directly obs erved by the absorption of a second sound wave probing the areal condu ctivity of the photogenerated charges.