Polarisation effects of the dynamical Stark effect of excitons in quantum wells

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Abstract
The authors study the polarisation properties of the dynamical Stark effect of excitons in semiconductor quantum wells. They start from a four-band density matrix theory involving the heavy- and light-hole band and the two lowest conduction subbands. The set of equations of motion contains the dynamics relevant for both Frohlich-type experiments (pumping with a carbon dioxide laser) and the case of pumping a few exciton rydbergs below the exciton line. The authors perform the relevant projections based on excitonic eigenstates and study the resulting 'few-level' systems. From this they calculate the change in the susceptibility tensor with respect to a weak probe beam caused by a pump beam with specified polarisation and frequency.