Coherent nonlinear propagation of ultrafast electric field-transients through intersubband resonances

Summary form only given. Low-dimensioial semiconductors are promising candidates for implementing quantum computing and ultrafast coherent optical switching. So far, most research concentrates on interband or excitonic excitations whereas intersubband (IS) transitions in quantum wells (QWs) have been less explored. Recent developments like controlled shaping and time-resolved detection of electric field transients in the mid-infrared spectral range (/spl lambda/ = 5 to 20 /spl mu/m) allow to investigate and directly manipulate coherent IS excitations in the time domain. A key parameter in any optical switching process is the required switching power. We demonstrate for the first time coherent nonlinear control of IS excitations in GaAs/AlGaAs QWs by extremely weak electric field-transients of sub-picojoule energy.