Quantum control of electron transfer

We explore electron transfer in double quantum well structures induced by f emtosecond mid-infrared intersubband excitation. Spatial transfer of electr ons from one quantum well to its hole filled neighbor is detected by recomb ination luminescence. The process results in upconversion of the mid-infrar ed exciting light to near-infrared luminescence. Two mid-infrared pulses wi th variable time delay allow us to display the field and intensity autocorr elation function for the upconverted signal and measure the electron transf er dynamics. Electron transfer between two GaAs quantum wells separated by 300 nm can be saturated and the intensity autocorrelation function exhibits a slow 18 ps recovery. Transfer between wells separated by only 25 nm is c oherently controlled by the phase of the two collinear infrared pulses.