Microscopic theory of exciton coherent control and Rayleigh scattering in semiconductor quantum wells

Abstract

We present a bosonic description of excitons created by means of resonant optical pumping in a quantum well in the presence of a weak disorder potential. The excitonic collective state is a Glauber coherent state, closely related to that of photons but substantially different from that of few-level models. The theory, applying to the low-density regime, is used to explain various transient linear optical experiments involving resonantly excited excitons in GaAs quantum wells. In particular, we consider coherent control of the exciton density and spin, resonant Rayleigh scattering and scattering coherent control. Our quantum mechanical approach for light emission shows that excitonic secondary emission has a coherent component, in agreement with experiments.

Fermi-edge singularities in linear and nonlinear ultrafast spectroscopy

“…Moreover, the laser pulses are spectrally narrow ͑com-pared to the Fermi energy ⑀ F measured from the bottom of the conduction band͒ so that the photoexcited electrons have energies close to the Fermi level, but the pulses are shorter than T 2 so that transient coherent effects can be observed. 5 Our main findings are ͑i͒ CC of the energy absorbed by the system ͑the analogous of CC of the exciton density [12][13][14] ͒ can be performed in doped samples. CC oscillations show a characteristic phase shift, which depends on the exponent of the continuous wave FES.…”