Coherent control of carrier-carrier scattering in bulk GaAs in the regime of Coulomb quantum kinetics

Summary form only given. In a coherent control four-wave mixing (FWM) experiment, a first pulse, 1, can excite a certain electron-hole pair density n/sub eh/ in a semiconductor. Because this density is connected with interband coherence, a second phase locked and time-delayed pulse, 1´, adjusted for destructive interference, can lead to a coherent reemission of photons. As a result, a first light pulse has created electron-hole pairs and a second light pulse has annihilated these electron-hole pairs again. A third pulse, leads to a FWM-signal and can thus probe the remaining density. This form of coherent control has been demonstrated on excitons and on continuum transitions. In the low density regime, one can argue, however, that one merely sees the interference of two independent FWM-signals on the detector. While there is no true contradiction in theory, the latter reasoning obviously questions severely whether such experiments are really evidence for the coherent control of the carrier density.