Electromechanical tuning of vertically-coupled photonic crystal nanobeams

We present the design, the fabrication and the characterization of a tunable one-dimensional (1D) photonic crystal cavity (PCC) etched on two vertically-coupled GaAs nanobeams. A novel fabrication method which prevents their adhesion under capillary forces is introduced. We discuss a design to increase the flexibility of the structure and we demonstrate a large reversible and controllable electromechanical wavelength tuning (> 15 nm) of the cavity modes.Comment: 11 pages, 4 figure

High beta lasing in micropillar cavities with adiabatic layer design

We report on lasing in optically pumped adiabatic micropillar cavities, based on the AlAs/GaAs material system. A detailed study of the threshold pump power and the spontaneous emission beta factor in the lasing regime for different diameters d(c) is presented. We demonstrate a reduction of the threshold pump power by over 2 orders of magnitude from d(c) = 2.25 mu m down to 0.95 mu m. Lasing with beta factors exceeding 0.5 shows that adiabatic micropillars are operating deeply in the cavity quantum electrodynamics regime.Publisher PDFPeer reviewe

Gallium Arsenide (GaAs) Quantum Photonic Waveguide Circuits

Integrated quantum photonics is a promising approach for future practical and large-scale quantum information processing technologies, with the prospect of on-chip generation, manipulation and measurement of complex quantum states of light. The gallium arsenide (GaAs) material system is a promising technology platform, and has already successfully demonstrated key components including waveguide integrated single-photon sources and integrated single-photon detectors. However, quantum circuits capable of manipulating quantum states of light have so far not been investigated in this material system. Here, we report GaAs photonic circuits for the manipulation of single-photon and two-photon states. Two-photon quantum interference with a visibility of 94.9 +/- 1.3% was observed in GaAs directional couplers. Classical and quantum interference fringes with visibilities of 98.6 +/- 1.3% and 84.4 +/- 1.5% respectively were demonstrated in Mach-Zehnder interferometers exploiting the electro-optic Pockels effect. This work paves the way for a fully integrated quantum technology platform based on the GaAs material system.Comment: 10 pages, 4 figure

Waveguide single-photon detectors for integrated quantum photonic circuits

The generation, manipulation and detection of quantum bits (qubits) encoded on single photons is at the heart of quantum communication and optical quantum information processing. The combination of single-photon sources, passive optical circuits and single-photon detectors enables quantum repeaters and qubit amplifiers, and also forms the basis of all-optical quantum gates and of linear-optics quantum computing. However, the monolithic integration of sources, waveguides and detectors on the same chip, as needed for scaling to meaningful number of qubits, is very challenging, and previous work on quantum photonic circuits has used external sources and detectors. Here we propose an approach to a fully-integrated quantum photonic circuit on a semiconductor chip, and demonstrate a key component of such circuit, a waveguide single-photon detector. Our detectors, based on superconducting nanowires on GaAs ridge waveguides, provide high efficiency (20%) at telecom wavelengths, high timing accuracy (60 ps), response time in the ns range, and are fully compatible with the integration of single-photon sources, passive networks and modulators.Comment: 11 pages, 4 figure

Beiträge zur Geschichte des Landkreises Regensburg 40

Marginalien von 12 Autoren, darin: Sparkasse Regensburg: Silbermedaille 'Mittelalter in Ostbayern' (S. 3); Fendl, Josef: Heimatgeschichte in zwei Dialekt-Monologen (S. 3-6); Deml, Hans: Eine Karriere im Mittelalter: Hans Vetter aus "Kohlßriedt" (S. 7); Schwaiger, Dieter: Kriegsnöte in der Pfarrei Deuerling (S. 8-11); Donau Post: Frauenzells großer Baumeister kam aus Wörth (S. 12); Raab, Michael: Großer Hexenprozeß zu Geisling 1689-1691 (S. 13-17); Lermer, Xaver: Die Donau (bei Geisling) / Haidau - Haidauer Weg / Das Jahr 1809 (S. 18-21); Mittelbayerische Zeitung: Zwei Aufsätze zur Schulgeschichte Altenthanns: Für Bemühungen wird nur Spott und Grobheit gebracht - Von Altenthann wollten junge Lehrer sofort wieder weg, Bei unehelichen Kindern verlor Altenthann die Geduld (S. 22-25); Donau Post: In Wolfskofen fanden sie eine neue Heimat (S. 25-26); Mittelbayerische Zeitung: Vor 25 Jahren Fähre von Pfatter nach Wörth eingestellt - Beim Uferer Karl Schiller gingen die Nazi-Größen baden (S. 27); Staudigl, Franz Xaver: Kampf um die Glaubens- und Gewissensfreiheit (S. 28-36); Koschier, Franz: Der Festzug - Hinweise für Organisation und Gestaltung (S. 37-40); Fendl, Josef: Die Kapelle bei St. Johann (S. 40