Einige ALGOL-Programme für Sortierverfahren

Blätter der DGVFM - Several ALGOL programs for sorting procedures are presented and their organization and applications are briefly discussed. Five of the programmes were checked on an IBM 650...     

Flying qubits and entangled photons

Efficient generation of polarized single photons or entangled photon pairs is crucial for the implementation of quantum key distribution (QKD) systems. Self organized semiconductor quantum dots (QDs) are capable of emitting on demand one polarized photon or an entangled photon pair upon current injection. Highly efficient single‐photon sources consist of a pin structure inserted into a microcavity where single electrons and holes are funneled into an InAs QD via a submicron AlOx aperture, leading to emission of single polarized photons with record purity of the spectrum and non‐classicality of the photons. A new QD site‐control technique is based on using the surface strain field of an AlO_x current aperture below the QD. GaN/AlN QD based devices are promising to operate at room temperature and reveal a fine‐structure splitting (FSS) depending inversely on the QD size. Large GaN/AlN QDs show disappearance of the FSS. Theory also suggests QDs grown on (111)‐oriented GaAs substrates as source of entangled photon pairs.     

Preparation of Cr2O3-Al2O3 Solid Solutions by Reactive Magnetron Sputtering

 (Al,Cr)₂O₃ layers were deposited on cemented carbide insert tips at a substrate temperature of 500 °C by means of reactive magnetron sputtering. An Al target was sputtered in RF mode and a Cr target in DC mode simultaneously in an oxygen/argon plasma. The influence of the Al and Cr sputter power and of the oxygen partial pressure on composition and structure of the (Al,Cr)₂O₃ layers as well as on the binding states of their components were investigated. Special attention was paid to the interpretation of the O ls and O-KLL fine structure and peak shifts. For the binary phases γ-Al₂O₃ and Cr₂O₃, a good agreement with literature values was observed in each case. In case of the ternary phases a continuous shift of the energetic position of the O1s peak, the O-KL₂₃L₂₃ transition and the modified Auger parameter α ′ of oxygen between the two binary phases γ-Al₂O₃ and Cr₂O₃ could be detected, indicating a wide range of solid solubility between Al₂O₃ and Cr₂O₃. As revealed by grazing incidence X-ray diffraction, the crystallinity of the ternary phases is less pronounced as compared to the binaries and increases with increasing oxygen flow rate.