Multiple-photon resolving fiber-loop detector

We show first reconstructions of the photon-number distribution obtained with a multi-channel fiber-loop detector. Apart from analyzing the statistics of light pulses this device can serve as a sophisticated postselection device for experiments in quantum optics and quantum information. We quantify its efficiency by means of the Fisher information and compare it to the efficiency of the ideal photodetector.Comment: 5 pages, 6 figure

Is Camouflaging Autistic Traits Associated with Suicidal Thoughts and Behaviours? Expanding the Interpersonal Psychological Theory of Suicide in an Undergraduate Student Sample

The current study explored whether people who camouflage autistic traits are more likely to experience thwarted belongingness and suicidality, as predicted by the Interpersonal Psychological Theory of Suicide (IPTS). 160 undergraduate students (86.9% female, 18–23 years) completed a cross-sectional online survey from 8th February to 30th May 2019 including self-report measures of thwarted belongingness and perceived burdensomeness, autistic traits, depression, anxiety, camouflaging autistic traits, and lifetime suicidality. Results suggest that camouflaging autistic traits is associated with increased risk of experiencing thwarted belongingness and lifetime suicidality. It is important for suicide theories such as the IPTS to include variables relevant to the broader autism phenotype, to increase applicability of models to both autistic and non-autistic people

A calcium ion in a cavity as a controlled single-photon source

We present a single calcium ion, coupled to a high-finesse cavity, as an almost ideal system for the controlled generation of single photons. Photons from a pump beam are Raman-scattered by the ion into the cavity mode, which subsequently emits the photon into a well-defined output channel. In contrast with comparable atomic systems, the ion is localized at a fixed position in the cavity mode for indefinite times, enabling truly continuous operation of the device. We have performed numeric calculations to assess the performance of the system and present the first experimental indication of single-photon emission in our set-up

A Measurement Invariance Analysis of the Interpersonal Needs Questionnaire and Acquired Capability for Suicide Scale in Autistic and Non-Autistic Adults.

Background: Autistic adults are more likely to engage in suicidal thoughts and behaviors, but there is little research to explore the underlying reasons. It is unclear whether self-report suicide scales that have been designed for non-autistic people accurately measure suicide risk constructs in autistic people. Therefore, this study explored, for the first time, whether the measurement properties of the self-report scales of the Interpersonal Theory of Suicide are equivalent in autistic and non-autistic adults. Methods: In this study, responses from 342 autistic and 353 non-autistic people on the Interpersonal Needs Questionnaire-10 (INQ-10) and Acquired Capability for Suicide Scale-Fearlessness about Death (ACSS-FAD) were compared by using measurement invariance analysis. Data were gathered through an online cross-sectional survey of the self-report measures. Results: Results suggest that measurement properties of the INQ-10 were different in autistic people. Autistic characteristics, such as different theory of mind and preference for concrete language, may have led the scale items to load differently on the factors in the autistic group than in the non-autistic group. The measurement properties of the ACSS-FAD were invariant between autistic and non-autistic people. Conclusions: Scores on the INQ-10 cannot be meaningfully compared between autistic and non-autistic people due to different measurement properties. Future research could explore how autistic people experience the concepts of burdensomeness and belonging, to consider how measures could accurately capture this. This would allow researchers to explore the role of these constructs in the development of suicidal thoughts and behaviors in autistic people. Clinicians should be aware that suicide risk factors may present differently in autistic people. Scores on the ACSS-FAD can be meaningfully compared, but the negatively worded scale items may pose similar response difficulties to autistic and non-autistic people

An entangled two photon source using biexciton emission of an asymmetric quantum dot in a cavity

A semiconductor based scheme has been proposed for generating entangled photon pairs from the radiative decay of an electrically-pumped biexciton in a quantum dot. Symmetric dots produce polarisation entanglement, but experimentally-realised asymmetric dots produce photons entangled in both polarisation and frequency. In this work, we investigate the possibility of erasing the `which-path' information contained in the frequencies of the photons produced by asymmetric quantum dots to recover polarisation-entangled photons. We consider a biexciton with non-degenerate intermediate excitonic states in a leaky optical cavity with pairs of degenerate cavity modes close to the non-degenerate exciton transition frequencies. An open quantum system approach is used to compute the polarisation entanglement of the two-photon state after it escapes from the cavity, measured by the visibility of two-photon interference fringes. We explicitly relate the two-photon visibility to the degree of Bell-inequality violation, deriving a threshold at which Bell-inequality violations will be observed. Our results show that an ideal cavity will produce maximally polarisation-entangled photon pairs, and even a non-ideal cavity will produce partially entangled photon pairs capable of violating a Bell-inequality.Comment: 16 pages, 10 figures, submitted to PR

Ranking ligand affinity for the DNA minor groove by experiment and simulation

The structural and thermodynamic basis for the strength and selectivity of the interactions of minor-groove binders (MGBs) with DNA is not fully understood. In 2003 we reported the first example of a thiazole containing MGB that bound in a phase shifted pattern that spanned 6 base-pairs rather than the usual 4 (for tricyclic distamycin-like compounds). Since then, using DNA footprinting, nuclear magnetic resonance spectroscopy, isothermal titration calorimetry and molecular dynamics, we have established that the flanking bases around the central 4 being read by the ligand have subtle effects on recognition. We have investigated the effect of these flanking sequences on binding and the reasons for the differences and established a computational method to rank ligand affinity against varying DNA sequences

User's Guide for MetView: A Meteorological Display and Assessment Tool

MetView Version 2.0 is an easy-to-use model for accessing, viewing, and analyzing meteorological data. MetView provides both graphical and numerical displays of data. It can accommodate data from an extensive meteorological monitoring network that includes near-surface monitoring locations, instrumented towers, sodars, and meteorologist observations. MetView is used operationally for both routine, emergency response, and research applications at the U.S. Department of Energy's Hanford Site. At the Site's Emergency Operations Center, MetView aids in the access, visualization, and interpretation of real-time meteorological data. Historical data can also be accessed and displayed. Emergency response personnel at the Emergency Operations Center use MetView products in the formulation of protective action recommendations and other decisions. In the initial stage of an emergency, MetView can be operated using a very simple, five-step procedure. This first-responder procedure allows non-technical staff to rapidly generate meteorological products and disseminate key information. After first-responder information products are produced, the Emergency Operations Center's technical staff can conduct more sophisticated analyses using the model. This may include examining the vertical variation in winds, assessing recent changes in atmospheric conditions, evaluating atmospheric mixing rates, and forecasting changes in meteorological conditions. This user's guide provides easy-to-follow instructions for both first-responder and routine operation of the model. Examples, with explanations, are provided for each type of MetView output display. Information is provided on the naming convention, format, and contents of each type of meteorological data file used by the model area. This user's guide serves as a ready reference for experienced MetView users and a training manual for new users