164 research outputs found
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
BeitrÀge 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 "KohlĂriedt" (S. 7); Schwaiger, Dieter: Kriegsnöte in der Pfarrei Deuerling (S. 8-11); Donau Post: Frauenzells groĂer Baumeister kam aus Wörth (S. 12); Raab, Michael: GroĂer HexenprozeĂ 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 AufsĂ€tze zur Schulgeschichte Altenthanns: FĂŒr BemĂŒhungen 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 FĂ€hre von Pfatter nach Wörth eingestellt - Beim Uferer Karl Schiller gingen die Nazi-GröĂen baden (S. 27); Staudigl, Franz Xaver: Kampf um die Glaubens- und Gewissensfreiheit (S. 28-36); Koschier, Franz: Der Festzug - Hinweise fĂŒr Organisation und Gestaltung (S. 37-40); Fendl, Josef: Die Kapelle bei St. Johann (S. 40
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