Quantum random number generation using a solid state single photon source

© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only. In this work we couple bright room-Temperature single-photon emission from a hexagonal boron nitride atomic defect into a laser-written photonic chip. We perform single photon state manipulation with evanescently coupled waveguides acting as a multiple beam splitter, and generate a superposition state maintaining single photon purity. We demonstrate that such states can be utilized for quantum random number generation

Photonic waveguide engineering using pulsed lasers - A novel approach for non-clean room fabrication!

Over the last 25 years has seen an unprecedented increase in the growth of phonic components based on semiconductor and solid-state lasers, glass and polymer based optical fibres, and organic LEDs. Emerging technology for component engineering must embed dissimilar materials based devices into an integrated form which is more efficient. In this article, we demonstrate techniques for overcoming the materials related limitations by adopting thin-film deposition techniques based on nano- and femto-second pulsed laser deposition. Three examples of thin-film fabrication for near-IR devices using Er3+-ion doped glass-on-GaAs, Er3+-ion doped glass-polydimethyl silane (PDMS) polymer, and Tm3+-doped nano-silicon thin films and gain medium waveguides are discussed. The modelling tools are used a priori for waveguide engineering for ascertaining the extent to which the structural incompatibility due to mismatch strain can be minimized. The structure and spectroscopic properties of Er3+- ion doped thin films on silica, polymer, and semiconductor GaAs substrates were examined in detail and are reported. We demonstrate the formation of glass-polymer superlattice structures for waveguide fabrication for overcoming the solubility limits of Er3+-ions in PDMS polymers. For inscribing waveguides in superlattice structures and nano silicon structures, the ablation machining using fs-pulsed Ti-sapphire laser was used, and the resulting spectroscopic properties of waveguides are discussed.The authors acknowledge the financial support from RCUK Basic Technology project (EP/D048692/1).This is the accepted manuscript. The final version is available from IEEE at http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6876466

Quasi-BIC Resonant Enhancement of Second-Harmonic Generation in WS2 Monolayers.

Atomically thin monolayers of transition metal dichalcogenides (TMDs) have emerged as a promising class of novel materials for optoelectronics and nonlinear optics. However, the intrinsic nonlinearity of TMD monolayers is weak, limiting their functionalities for nonlinear optical processes such as frequency conversion. Here we boost the effective nonlinear susceptibility of a TMD monolayer by integrating it with a resonant dielectric metasurface that supports pronounced optical resonances with high quality factors: bound states in the continuum (BICs). We demonstrate that a WS2 monolayer combined with a silicon metasurface hosting BICs exhibits enhanced second-harmonic intensity by more than 3 orders of magnitude relative to a WS2 monolayer on top of a flat silicon film of the same thickness. Our work suggests a pathway to employ high-index dielectric metasurfaces as hybrid structures for enhancement of TMD nonlinearities with applications in nonlinear microscopy, optoelectronics, and signal processing

Tomography of quantum dots in a non-hermitian photonic chip

© 2019 IEEE. Quantum optical information systems offer the potential for secure communication and fast quantum computation. To fully characterise a quantum optical system one has to use quantum tomography [1]. Integration of quantum optics onto photonic chips provides advantages such as miniaturisation and stability, and also significantly improves quantum tomography using both re-configurable [2], and more recently, simpler static designs [3,4]. These on-chip designs have, so far, only used probabilistic single photon sources. Here we are working towards quantum tomography using a true deterministic source - a quantum dot. The scheme of the proposed experiment is shown in Fig. 1A. So far we have fabricated and characterised the performance of an InGaAs quantum dot monolithically integrated into a microlens [5], and completed the design, fabrication and classical characterisation of a photonic chip for quantum tomography

Interplay of Mre11 Nuclease with Dna2 plus Sgs1 in Rad51-Dependent Recombinational Repair

The Mre11/Rad50/Xrs2 complex initiates IR repair by binding to the end of a double-strand break, resulting in 5′ to 3′ exonuclease degradation creating a single-stranded 3′ overhang competent for strand invasion into the unbroken chromosome. The nuclease(s) involved are not well understood. Mre11 encodes a nuclease, but it has 3′ to 5′, rather than 5′ to 3′ activity. Furthermore, mutations that inactivate only the nuclease activity of Mre11 but not its other repair functions, mre11-D56N and mre11-H125N, are resistant to IR. This suggests that another nuclease can catalyze 5′ to 3′ degradation. One candidate nuclease that has not been tested to date because it is encoded by an essential gene is the Dna2 helicase/nuclease. We recently reported the ability to suppress the lethality of a dna2Δ with a pif1Δ. The dna2Δ pif1Δ mutant is IR-resistant. We have determined that dna2Δ pif1Δ mre11-D56N and dna2Δ pif1Δ mre11-H125N strains are equally as sensitive to IR as mre11Δ strains, suggesting that in the absence of Dna2, Mre11 nuclease carries out repair. The dna2Δ pif1Δ mre11-D56N triple mutant is complemented by plasmids expressing Mre11, Dna2 or dna2K1080E, a mutant with defective helicase and functional nuclease, demonstrating that the nuclease of Dna2 compensates for the absence of Mre11 nuclease in IR repair, presumably in 5′ to 3′ degradation at DSB ends. We further show that sgs1Δ mre11-H125N, but not sgs1Δ, is very sensitive to IR, implicating the Sgs1 helicase in the Dna2-mediated pathway

Adaptive Lévy processes and area-restricted search in human foraging

A considerable amount of research has claimed that animals’ foraging behaviors display movement lengths with power-law distributed tails, characteristic of Lévy flights and Lévy walks. Though these claims have recently come into question, the proposal that many animals forage using Lévy processes nonetheless remains. A Lévy process does not consider when or where resources are encountered, and samples movement lengths independently of past experience. However, Lévy processes too have come into question based on the observation that in patchy resource environments resource-sensitive foraging strategies, like area-restricted search, perform better than Lévy flights yet can still generate heavy-tailed distributions of movement lengths. To investigate these questions further, we tracked humans as they searched for hidden resources in an open-field virtual environment, with either patchy or dispersed resource distributions. Supporting previous research, for both conditions logarithmic binning methods were consistent with Lévy flights and rank-frequency methods–comparing alternative distributions using maximum likelihood methods–showed the strongest support for bounded power-law distributions (truncated Lévy flights). However, goodness-of-fit tests found that even bounded power-law distributions only accurately characterized movement behavior for 4 (out of 32) participants. Moreover, paths in the patchy environment (but not the dispersed environment) showed a transition to intensive search following resource encounters, characteristic of area-restricted search. Transferring paths between environments revealed that paths generated in the patchy environment were adapted to that environment. Our results suggest that though power-law distributions do not accurately reflect human search, Lévy processes may still describe movement in dispersed environments, but not in patchy environments–where search was area-restricted. Furthermore, our results indicate that search strategies cannot be inferred without knowing how organisms respond to resources–as both patched and dispersed conditions led to similar Lévy-like movement distributions

Predictors of quality of care in mental health supported accommodation services in England: a multiple regression modelling study.

BACKGROUND: Specialist mental health supported accommodation services are a key component to a graduated level of care from hospital to independently living in the community for people with complex, longer term mental health problems. However, they come at a high cost and there has been a lack of research on the quality of these services. The QuEST (Quality and Effectiveness of Supported tenancies) study, a five-year programme of research funded by the National Institute for Health Research, aimed to address this. It included the development of the first standardised quality assessment tool for supported accommodation services, the QuIRC-SA (Quality Indicator for Rehabilitative Care - Supported Accommodation). Using data collected from the QuIRC-SA, we aimed to identify potential service characteristics that were associated with quality of care. METHODS: Data collected from QuIRC-SAs with 150 individual services in England (28 residential care, 87 supported housing and 35 floating outreach) from four different sources were analysed using multiple regression modelling to investigate associations between service characteristics (local authority area index score, total beds/spaces, staffing intensity, percentage of male service users and service user ability) and areas of quality of care (Living Environment, Therapeutic Environment, Treatments and Interventions, Self-Management and Autonomy, Social Interface, Human Rights and Recovery Based Practice). RESULTS: The local authority area in which the service is located, the service size (number of beds/places) and the usual expected length of stay were each negatively associated with up to six of the seven QuIRC-SA domains. Staffing intensity was positively associated with two domains (Therapeutic Environment and Treatments and Interventions) and negatively associated with one (Human Rights). The percentage of male service users was positively associated with one domain (Treatments and Interventions) and service user ability was not associated with any of the domains. CONCLUSIONS: This study identified service characteristics associated with quality of care in specialist mental health supported accommodation services that can be used in the design and specification of services

Thrombosis Is Reduced by Inhibition of COX-1, but Unaffected by Inhibition of COX-2, in an Acute Model of Platelet Activation in the Mouse

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

CD98hc facilitates B cell proliferation and adaptive humoral immunity.

The proliferation of antigen-specific lymphocytes and resulting clonal expansion are essential for adaptive immunity. We report here that B cell-specific deletion of the heavy chain of CD98 (CD98hc) resulted in lower antibody responses due to total suppression of B cell proliferation and subsequent plasma cell formation. Deletion of CD98hc did not impair early B cell activation but did inhibit later activation of the mitogen-activated protein kinase Erk1/2 and downregulation of the cell cycle inhibitor p27. Reconstitution of CD98hc-deficient B cells with CD98hc mutants showed that the integrin-binding domain of CD98hc was required for B cell proliferation but that the amino acid-transport function of CD98hc was dispensable for this. Thus, CD98hc supports integrin-dependent rapid proliferation of B cells. We propose that the advantage of adaptive immunity favored the appearance of CD98hc in vertebrates

Precision Orbit of δ Delphini and Prospects for Astrometric Detection of Exoplanets

This is the author accepted manuscript. The final version is available from American Astronomical Society / IOP Publishing via the DOI in this record.Combining visual and spectroscopic orbits of binary stars leads to a determination of the full 3D orbit, individual masses, and distance to the system. We present a full analysis of the evolved binary system δ Delphini using astrometric data from the MIRC and PAVO instruments on the CHARA long-baseline interferometer, 97 new spectra from the Fairborn Observatory, and 87 unpublished spectra from the Lick Observatory. We determine the full set of orbital elements for δ Del, along with masses of 1.78 ± 0.07 M ⊙ and 1.62 ± 0.07 M ⊙ for each component, and a distance of 63.61 ± 0.89 pc. These results are important in two contexts: for testing stellar evolution models and for defining the detection capabilities for future planet searches. We find that the evolutionary state of this system is puzzling, as our measured flux ratios, radii, and masses imply a ~200 Myr age difference between the components, using standard stellar evolution models. Possible explanations for this age discrepancy include mass transfer scenarios with a now-ejected tertiary companion. For individual measurements taken over a span of two years, we achieve 2 M J on orbits >0.75 au around individual components of hot binary stars via differential astrometry.This work is based upon observations obtained with the Georgia State University Center for High Angular Resolution Astronomy Array at Mount Wilson Observatory. The CHARA Array is supported by the National Science Foundation under Grants No. AST-1211929 and AST-1411654. Institutional support has been provided from the GSU College of Arts and Sciences and the GSU Office of the Vice President for Research and Economic Development. This research has made use of the Jean-Marie Mariotti Center SearchCal service2 . JDM and TG wish to gratefully acknowledge support by NASA XRP Grant NNX16AD43G. Astronomy at Tennessee State University is supported by the state of Tennessee through its Centers of Excellence program. SK acknowledges support from an European Research Council Starting Grant (Grant Agreement No. 639889) and STFC Rutherford Fellowship (ST/J004030/1). D.H. acknowledges support by the National Aeronautics and Space Administration under Grant NNX14AB92G issued through the Kepler Participating Scientist Program. TRW acknowledges the support of the Villum Foundation (research grant 10118)