Short Term Topological Changes of Coronal Holes Associated with Prominence Eruptions and Subsequent CMEs

We study the short--term topological changes of equatorial and polar coronal hole (CH) boundaries, such as a variation of their area and disintegration, associated to reconnection with nearby (within 15$^\circ$ distance) quiescent prominence magnetic fields leading to eruptions and subsequent Coronal Mass Ejections (CMEs). The examples presented here correspond to the recent solar minimum years 2008 and 2009. We consider a temporal window of one day between the CH topological changes and the start and end times of prominence eruptions and onset of CMEs. To establish this association we took into account observational conditions related to the instability of prominence/filaments, the occurrence of a CME, as well as the subsequent evolution after the CME. We found an association between short--term local topological changes in CH boundaries and the formation/disappearance of bright points near them, as well as, between short--term topological changes within the whole CH and eruptions of nearby quiescent prominences followed by the appearance of one or more CMEs.Comment: 15 pages, 11 figures; Journal Advances Space Research (2012

Integrating Research Data Management into Geographical Information Systems

Ocean modelling requires the production of high-fidelity computational meshes upon which to solve the equations of motion. The production of such meshes by hand is often infeasible, considering the complexity of the bathymetry and coastlines. The use of Geographical Information Systems (GIS) is therefore a key component to discretising the region of interest and producing a mesh appropriate to resolve the dynamics. However, all data associated with the production of a mesh must be provided in order to contribute to the overall recomputability of the subsequent simulation. This work presents the integration of research data management in QMesh, a tool for generating meshes using GIS. The tool uses the PyRDM library to provide a quick and easy way for scientists to publish meshes, and all data required to regenerate them, to persistent online repositories. These repositories are assigned unique identifiers to enable proper citation of the meshes in journal articles.Comment: Accepted, camera-ready version. To appear in the Proceedings of the 5th International Workshop on Semantic Digital Archives (http://sda2015.dke-research.de/), held in Pozna\'n, Poland on 18 September 2015 as part of the 19th International Conference on Theory and Practice of Digital Libraries (http://tpdl2015.info/

Efficient Photon Coupling from a Diamond Nitrogen Vacancy Centre by Integration with Silica Fibre

A central goal in quantum information science is to efficiently interface photons with single optical modes for quantum networking and distributed quantum computing. Here, we introduce and experimentally demonstrate a compact and efficient method for the low-loss coupling of a solid-state qubit, the nitrogen vacancy (NV) centre in diamond, with a single-mode optical fibre. In this approach, single-mode tapered diamond waveguides containing exactly one high quality NV memory are selected and integrated on tapered silica fibres. Numerical optimization of an adiabatic coupler indicates that near-unity-efficiency photon transfer is possible between the two modes. Experimentally, we find an overall collection efficiency between 18-40 % and observe a raw single photon count rate above 700 kHz. This integrated system enables robust, alignment-free, and efficient interfacing of single-mode optical fibres with single photon emitters and quantum memories in solids

Target detection through quantum illumination

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2012."February 2012." Cataloged from PDF version of thesis.Includes bibliographical references (p. 69-70).Classical target detection can suffer large error probabilities in noisy and lossy environments when noise photons are mistaken for signal photons reflected from an object. It has been shown theoretically that the correlation between entangled photons can be used to better discriminate between the signal photons reflected by an object and noise photons, thus reducing the probability of error [13, 15, 17, 7, 6]. This thesis presents the first experimental implementation of target detection enhanced by quantum illumination (QI). Nondegenerate, time entangled signal and idler beams are created through Type-O spontaneous parametric downconversion (SPDC). The signal is attenuated and combined with large levels of noise. The signal is phase modulated to improve the observation by shifting it from DC to 16 kHz. The return signal and idler are recombined in an optical parametric amplifier (OPA) which captures the phase correlation between the two beams. It is found that only 10% of the total signal and idler photons interact at the OPA due to the multi-mode nature of the SPDC emission which does not match the pump spatial mode and thus experience lower gains at the OPA. Considering only the power interacting at the OPA, the signal-to-noise ratio (SNR) of QI agrees with the theoretical model.by Sara L. Mouradian.M.Eng

Entanglement-Enhanced Sensing in a Lossy and Noisy Environment

Nonclassical states are essential for optics-based quantum information processing, but their fragility limits their utility for practical scenarios in which loss and noise inevitably degrade, if not destroy, nonclassicality. Exploiting nonclassical states in quantum metrology yields sensitivity advantages over all classical schemes delivering the same energy per measurement interval to the sample being probed. These enhancements, almost without exception, are severely diminished by quantum decoherence. Here, we experimentally demonstrate an entanglement-enhanced sensing system that is resilient to quantum decoherence. We employ entanglement to realize a 20% signal-to-noise ratio improvement over the optimum classical scheme in an entanglement-breaking environment plagued by 14 dB of loss and a noise background 75 dB stronger than the returned probe light. Our result suggests that advantageous quantum-sensing technology could be developed for practical situations.United States. Army Research Office (Grant W911NF-10-1-0430)United States. Office of Naval Research (Grant N00014-13-1-0774

Enhanced nonlinear spectral compression in fiber by external sinusoidal phase modulation

We propose a new, simple approach to enhance the spectral compression process arising from nonlinear pulse propagation in an optical fiber. We numerically show that an additional sinusoidal temporal phase modulation of the pulse enables efficient reduction of the intensity level of the side lobes in the spectrum that are produced by the mismatch between the initial linear negative chirp of the pulse and the self-phase modulation-induced nonlinear positive chirp. Remarkable increase of both the extent of spectrum narrowing and the quality of the compressed spectrum is afforded by the proposed approach across a wide range of experimentally accessible parameters

TELEMAC model archive: Integrating open–source tools for the management and visualisation of model data

Water Qualit