INTERSUBBAND WAVE-PACKET INTERFEROMETRY WITH SEMICONDUCTOR NANOSTRUCTURES

We study the use of wave packet interferometry in modulation-doped sem iconductor nanostructures. In suitably designed quantum well structure s, an electronic wave packet made of a coherent superposition of subba nd wave functions is created by a sub-picosecond laser pulse. After a given delay time, a second pulse, identical to the first, creates anot her wave packet. Under appropriate conditions these two packets interf ere, a process that affects the excited electron population. The depen dence of this excess population on the delay time is sensitive to the dephasing of the first wave packet, and this property can be used to s tudy the intersubband dephasing times. (C) 1998 Elsevier Science B.V.