54 research outputs found
P-REx: The Piston Reconstruction Experiment for Infrared Interferometry
For sensitive infrared interferometry, it is crucial to control the
differential piston evolution between the used telescopes. This is classically
done by the use of a fringe tracker. In this work, we develop a new method to
reconstruct the temporal piston variation from the atmosphere, by using
real-time data from adaptive optics wavefront sensing: the Piston
Reconstruction Experiment (P-REx). In order to understand the principle
performance of the system in a realistic multilayer atmosphere it is first
extensively tested in simulations. The gained insights are then used to apply
P-REx to real data, in order to demonstrate the benefit of using P-REx as an
auxiliary system in a real interferometer. All tests show positive results,
which encourages further research and eventually a real implementation.
Especially the tests on on-sky data showed that the atmosphere is, under decent
observing conditions, sufficiently well structured and stable, in order to
apply P-REx. It was possible to conveniently reconstruct the piston evolution
in two-thirds of the datasets from good observing conditions (r 30
cm). The main conclusion is that applying the piston reconstruction in a real
system would reduce the piston variation from around 10 m down to 1-2
m over timescales of up to two seconds. This suggests an application for
mid-infrared interferometry, for example for MATISSE at the VLTI or the LBTI.
P-REx therefore provides the possibility to improve interferometric
measurements without the need for more complex AO systems than already in
regular use at 8m-class telescopes.Comment: 15 pages, 13 figures, 5 tables. Accepted for publication by Monthly
Notices of the Royal Astronomical Societ
Single Molecule DNA Detection with an Atomic Vapor Notch Filter
The detection of single molecules has facilitated many advances in life- and
material-sciences. Commonly, it founds on the fluorescence detection of single
molecules, which are for example attached to the structures under study. For
fluorescence microscopy and sensing the crucial parameters are the collection
and detection efficiency, such that photons can be discriminated with low
background from a labeled sample. Here we show a scheme for filtering the
excitation light in the optical detection of single stranded labeled DNA
molecules. We use the narrow-band filtering properties of a hot atomic vapor to
filter the excitation light from the emitted fluorescence of a single emitter.
The choice of atomic sodium allows for the use of fluorescent dyes, which are
common in life-science. This scheme enables efficient photon detection, and a
statistical analysis proves an enhancement of the optical signal of more than
15% in a confocal and in a wide-field configuration.Comment: 9 pages, 5 figure
Vector magnetometry using silicon vacancies in 4H-SiC at ambient conditions
Point defects in solids promise precise measurements of various quantities.
Especially magnetic field sensing using the spin of point defects has been of
great interest recently. When optical readout of spin states is used, point
defects achieve optical magnetic imaging with high spatial resolution at
ambient conditions. Here, we demonstrate that genuine optical vector
magnetometry can be realized using the silicon vacancy in SiC, which has an
uncommon S=3/2 spin. To this end, we develop and experimentally test sensing
protocols based on a reference field approach combined with multi frequency
spin excitation. Our works suggest that the silicon vacancy in an
industry-friendly platform, SiC, has potential for various magnetometry
applications at ambient conditions
Change-Management an Hochschulen im Rahmen strategischer Digitalisierungsprojekte
Dieser Beitrag diskutiert die Notwendigkeit eines dauerhaft angelegten Change-Management-Prozesses im Kontext von Digitalisierungsvorhaben an Hochschulen. Anhand eines konkreten Beispiels wird gezeigt, wie ein solcher Prozess gestaltet werden kann, um die digitale Transformation an einer Hochschule voranzutreiben. Die Autorinnen und Autoren erachten dabei eine akteursspezifische Perspektive mit Handlungsvariablen zur Erhöhung der Veränderungsbereitschaft als zentrales Element. Zudem werden im Beitrag verschiedene Instrumente beschrieben, die im Kontext des diskutierten Projekts eingesetzt werden, um möglichst alle Interessengruppen der Hochschule systematisch und adäquat in den Veränderungsprozess miteinzubeziehen. Die Umsetzung entsprechender Prozesse und Instrumente profitiert dabei von einem agilen Projektmanagement. Erste Erfahrungen mit einer solchen expliziten Einführung und Gestaltung eines hochschulweiten Change-Management-Prozesses sind positiv. Allerdings steht eine umfassende Evaluation einzelner Instrumente und deren Integration noch aus. (DIPF/Orig.
Coherent electrical readout of defect spins in 4H-SiC by photo-ionization at ambient conditions
Quantum technology relies on proper hardware, enabling coherent quantum state
control as well as efficient quantum state readout. In this regard,
wide-bandgap semiconductors are an emerging material platform with scalable
wafer fabrication methods, hosting several promising spin-active point defects.
Conventional readout protocols for such defect spins rely on fluorescence
detection and are limited by a low photon collection efficiency. Here, we
demonstrate a photo-electrical detection technique for electron spins of
silicon vacancy ensembles in the 4H polytype of silicon carbide (SiC). Further,
we show coherent spin state control, proving that this electrical readout
technique enables detection of coherent spin motion. Our readout works at
ambient conditions, while other electrical readout approaches are often limited
to low temperatures or high magnetic fields. Considering the excellent maturity
of SiC electronics with the outstanding coherence properties of SiC defects the
approach presented here holds promises for scalability of future SiC quantum
devices
Quantum properties of dichroic silicon vacancies in silicon carbide
The controlled generation and manipulation of atom-like defects in solids has
a wide range of applications in quantum technology. Although various defect
centres have displayed promise as either quantum sensors, single photon
emitters or light-matter interfaces, the search for an ideal defect with
multi-functional ability remains open. In this spirit, we investigate here the
optical and spin properties of the V1 defect centre, one of the silicon vacancy
defects in the 4H polytype of silicon carbide (SiC). The V1 centre in 4H-SiC
features two well-distinguishable sharp optical transitions and a unique S=3/2
electronic spin, which holds promise to implement a robust spin-photon
interface. Here, we investigate the V1 defect at low temperatures using optical
excitation and magnetic resonance techniques. The measurements, which are
performed on ensemble, as well as on single centres, prove that this centre
combines coherent optical emission, with up to 40% of the radiation emitted
into the zero-phonon line (ZPL), a strong optical spin signal and long spin
coherence time. These results single out the V1 defect in SiC as a promising
system for spin-based quantum technologies
Scalable quantum photonics with single color centers in silicon carbide
Silicon carbide is a promising platform for single photon sources, quantum bits (qubits), and nanoscale sensors based on individual color centers. Toward this goal, we develop a scalable array of nanopillars incorporating single silicon vacancy centers in 4H-SiC, readily available for efficient interfacing with free-space objective and lensed-fibers. A commercially obtained substrate is irradiated with 2 MeV electron beams to create vacancies. Subsequent lithographic process forms 800 nm tall nanopillars with 400–1400 nm diameters. We obtain high collection efficiency of up to 22 kcounts/s optical saturation rates from a single silicon vacancy center while preserving the single photon emission and the optically induced electron-spin polarization properties. Our study demonstrates silicon carbide as a readily available platform for scalable quantum photonics architecture relying on single photon sources and qubits
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