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The exciton-polariton states of quantum wells embedded in planar semiconductor microcavities are usually described by assuming in-plane wave vector conservation. In this work we consider the two main k(parallel to)-scattering mechanisms, namely the polariton-phonon scattering and the in-plane structural disorder of the quantum well. We calculate the homogeneous and inhomogeneous broadening of the polariton levels and show that a detailed model of the scattering processes is essential for a theoretical derivation of recently observed features of the linear spectra.
We analyze the optical quantum control of impurity spins in proximity to a quantum dot. A laser pulse creates an exciton in the dot and controls the spins by indirect coupling. We show how to determine the control parameters using as an illustration the production of maximal spin entanglement. We consider errors in the quantum control due to the exciton radiative recombination. The control errors in the adiabatic and nonadiabatic case are compared to the threshold needed for scalable quantum computing.
We propose a scheme for the generation of photocurrent in bent quantum wires. We calculate the current using a generalized Landauer-Buttiker approach that takes into account the electromagnetic radiation. For circularly polarized light, we find that the curvature in the bent wire induces an asymmetry in the scattering coefficients for left and right moving electrons. This asymmetry results in a current at zero bias voltage. The effect is due to the geometry of the wire which transforms the photon angular momentum into translational motion for the electrons.
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