Exploring the limits of multiplexed photon-pair sources for the preparation of pure single-photon states

Current sources of heralded single photons based on nonlinear optics operate in a probabilistic manner. In order to build quantum-enhanced devices based around the use of single photons, compact, turn-key and deterministic sources are required. A possible solution is to multiplex a number of sources to increase the single-photon generation probability and in so doing reducing the waiting time to deliver large numbers of photons simultaneously, from independent sources. Previously it has been shown that, in the ideal case, 17 multiplexed sources allow deterministic generation of heralded single photons [Christ and Silberhorn, Phys. Rev. A 85, 023829 (2012)]. Here we extend this analysis to include undesirable effects of detector inefficiency and photon loss on a number of multiplexed sources using a variety of different detectors for heralding. We compare these systems for fixed signal-to-noise ratio to allow a direct comparison of performance for real- world heralded single photon sources.Comment: 10 pages, 7 figures. Equation 18 changed to include power of a half in the binomial facto

Temporal Loop Multiplexing: A resource efficient scheme for multiplexed photon-pair sources

Single photons are a vital resource for photonic quantum information processing. However, even state-of-the-art single photon sources based on photon-pair generation and heralding detection have only a low probability of delivering a single photon when one is requested. We analyse a scheme that uses a switched fibre delay loop to increase the delivery probability per time bin of single photons from heralded sources. We show that, for realistic experimental parameters, combining the output of up to 15 pulses can yield a performance improvement of a factor of 10. We consider the future performance of this scheme with likely component improvements.Comment: 5 pages, 4 figure

On the Structure of Lie Pseudo-Groups

We compare and contrast two approaches to the structure theory for Lie pseudo-groups, the first due to Cartan, and the second due to the first two authors. We argue that the latter approach offers certain advantages from both a theoretical and practical standpoint

The Oswald Clergy Burnout Scale: reliability, factor structure and preliminary application among Australian clergy

This study assesses the Oswald Clergy Burnout Scale (OCBI), the psychometric properties of which have not been previously described. Analysis of responses from a large number (N  = 3,012) of ministers in charge of Australian congregations showed that the scale’s internal reliability was satisfactory, and that the scale could be represented by two factors, identified, respectively, as the personal and social aspects of burnout. This structure was supported by confirmatory factor analysis. Several demographic and job-related variables that might relate to burnout were regressed on the total, personal and social factor scores. Age is the predominant (negative) predictor of burnout as measured by the total scale and the personal factor scores. All variables predict burnout as measured by the social factor. However, in all models, the predictor variables account for no more than 5% of the total variance. These findings suggest that demographic factors and working conditions are poor predictors of burnout among clergy

Psychological type and work-related psychological health among clergy in Australia, England and New Zealand

A sample of 3,715 clergy from Australia, England and New Zealand completed two indices of work-related psychological health, the Scale of Emotional Exhaustion in Ministry (negative affect) and the Satisfaction in Ministry Scale (positive affect), together with a measure of Jungian psychological type, the Francis Psychological Type Scales. The data were employed to establish three issues: the level of work-related psychological health among clergy; the psychological type profile of clergy; and the relationship between psychological type and individual differences in work-related psychological health. The data demonstrate that clergy display high levels of positive affect coupled with high levels of negative affect; that the predominant psychological type profile of clergy prefers introversion over extraversion, sensing over intuition, feeling over thinking, and judging over perceiving; and that psychological type is able to predict differences in work-related psychological health among clergy. Clergy who prefer introversion and thinking experience lower levels of work-related psychological health than clergy who prefer extraversion and feeling. The implications of these findings are discussed for developing effective and healthy Christian ministry

Growth or decline in the Church of England during the decade of Evangelism: did the Churchmanship of the Bishop matter?

The Decade of Evangelism occupied the attention of the Church of England throughout the 1990s. The present study employs the statistics routinely published by the Church of England in order to assess two matters: the extent to which these statistics suggest that the 43 individual dioceses finished the decade in a stronger or weaker position than they had entered it and the extent to which, according to these statistics, the performance of dioceses led by bishops shaped in the Evangelical tradition differed from the performance of dioceses led by bishops shaped in the Catholic tradition. The data demonstrated that the majority of dioceses were performing less effectively at the end of the decade than at the beginning, in terms of a range of membership statistics, and that the rate of decline varied considerably from one diocese to another. The only exception to the trend was provided by the diocese of London, which experienced some growth. The data also demonstrated that little depended on the churchmanship of the diocesan bishop in shaping diocesan outcomes on the performance indicators employed in the study

Controlled levels of protein modification through a chromatography-mediated bioconjugation.

Synthetically modified proteins are increasingly finding applications as well-defined scaffolds for materials. In practice it remains difficult to construct bioconjugates with precise levels of modification because of the limited number of repeated functional groups on proteins. This article describes a method to control the level of protein modification in cases where there exist multiple potential modification sites. A protein is first tagged with a handle using any of a variety of modification chemistries. This handle is used to isolate proteins with a particular number of modifications via affinity chromatography, and then the handle is elaborated with a desired moiety using an oxidative coupling reaction. This method results in a sample of protein with a well-defined number of modifications, and we find it particularly applicable to systems like protein homomultimers in which there is no way to discern between chemically identical subunits. We demonstrate the use of this method in the construction of a protein-templated light-harvesting mimic, a type of system which has historically been difficult to make in a well-defined manner