| Abstract: | Semiconductor quantum dots (QDs) are small objects that confine electrons and holes in all three dimensions. This confinement results in discrete spectrum of energy levels. This ‘atomic-like’ feature, together with their compatibility with modern semiconductor based microelectronics and optoelectronics, make QDs promising building block devices for future technologies involving quantum information processing. In particular, QDs are considered to be an excellent interface between photons, whose polarization state may carry quantum information from one site to another, and confined carriers' spins, whose states can be coherently manipulated locally. We study the optical properties of such single QDs, experimentally and theoretically. I will present experimental measurements of polarization sensitive spectroscopy using two non degenerate pulsed lasers. The resonances-rich spectrum is fully analyzed and understood for the first time. With this understanding, we succeed to coherently “write” and “read” the spin state of the confined neutral electron-heavy-hole pair (exciton) by a single light pulse. We thus demonstrate a one to one mapping between any point on the Poincar'e sphere of the light polarization to a corresponding point on the Bloch sphere of the exciton’s spin. |
