Testing nonlocality over 12.4 km of underground fiber with universal time-bin qubit analyzers

We experimentally demonstrate that the nonlocal nature of time-bin entangled photonic qubits persists when one or two qubits of the pair are converted to polarization qubits. This is possible by implementing a novel Universal Time-Bin Qubit Analyzer (UTBA), which, for the first time, allows analyzing time-bin qubits in any basis. We reveal the nonlocal nature of the emitted light by violating the Clauser-Horne-Shimony-Holt inequality with measurement bases exploring all the dimensions of the Bloch sphere. Moreover, we conducted experiments where one qubit is transmitted over a 12.4 km underground fiber link and demonstrate the suitability of our scheme for use in a real-world setting. The resulting entanglement can also be interpreted as hybrid entanglement between different types of degrees of freedom of two physical systems, which could prove useful in large scale, heterogeneous quantum networks. This work opens new possibilities for testing nonlocality and for implementing new quantum communication protocols with time-bin entanglement.Comment: 6 pages, 5 figure

Quantum storage of polarization qubits in birefringent and anisotropically absorbing materials

Storage of quantum information encoded into true single photons is an essential constituent of long-distance quantum communication based on quantum repeaters and of optical quantum information processing. The storage of photonic polarization qubits is, however, complicated by the fact that many materials are birefringent and have polarization-dependent absorption. Here we present and demonstrate a simple scheme that allows compensating for these polarization effects. The scheme is demonstrated using a solid-state quantum memory implemented with an ensemble of rare-earth ions doped into a biaxial yttrium orthosilicate ($Y_2SiO_5$) crystal. Heralded single photons generated from a filtered spontaneous parametric downconversion source are stored, and quantum state tomography of the retrieved polarization state reveals an average fidelity of $97.5 \pm 0.4$, which is significantly higher than what is achievable with a measure-and-prepare strategy.Comment: 7 pages, 3 figures, 1 table, corrected typos and added ref. 3

High-detection efficiency and low-timing jitter with amorphous superconducting nanowire single-photon detectors

Recent progress in the development of superconducting nanowire single-photon detectors (SNSPDs) made of amorphous material has delivered excellent performances, and has had a great impact on a range of research fields. Despite showing the highest system detection efficiency (SDE) ever reported with SNSPDs, amorphous materials typically lead to lower critical currents, which impacts on their jitter performance. Combining a very low jitter and a high SDE remains a challenge. Here, we report on highly efficient superconducting nanowire single-photon detectors based on amorphous MoSi, combining system jitters as low as 26 ps and a SDE of 80% at 1550 nm. We also report detailed observations on the jitter behaviour, which hints at intrinsic limitations and leads to practical implications for SNSPD performance

Flipping quantum coins

Coin flipping is a cryptographic primitive in which two distrustful parties wish to generate a random bit in order to choose between two alternatives. This task is impossible to realize when it relies solely on the asynchronous exchange of classical bits: one dishonest player has complete control over the final outcome. It is only when coin flipping is supplemented with quantum communication that this problem can be alleviated, although partial bias remains. Unfortunately, practical systems are subject to loss of quantum data, which restores complete or nearly complete bias in previous protocols. We report herein on the first implementation of a quantum coin-flipping protocol that is impervious to loss. Moreover, in the presence of unavoidable experimental noise, we propose to use this protocol sequentially to implement many coin flips, which guarantees that a cheater unwillingly reveals asymptotically, through an increased error rate, how many outcomes have been fixed. Hence, we demonstrate for the first time the possibility of flipping coins in a realistic setting. Flipping quantum coins thereby joins quantum key distribution as one of the few currently practical applications of quantum communication. We anticipate our findings to be useful for various cryptographic protocols and other applications, such as an online casino, in which a possibly unlimited number of coin flips has to be performed and where each player is free to decide at any time whether to continue playing or not.Comment: 17 pages, 3 figure

Évaluation d’implantation d’une expérience novatrice : le réseau intégré de services aux aînés des Bois-Francs

Consciente de l'existence de problèmes liés à la coordination des services rendus aux aînés sur son territoire, la Table de concertation des services de santé et de services sociaux des Bois-Francs dans la région Mauricie et du Centre-du-Québec implanta en février 1997, après deux ans de planification, un nouveau modèle de coordination des soins et des services aux personnes âgées en perte d'autonomie. Ce modèle est novateur car il combine le guichet ou porte d'entrée unique, la gestion de cas, le plan de services individualisé et la présence de trois niveaux de concertation : stratégique, tactique et clinique. Il a aussi la particularité de couvrir tout le continuum de soins et de services aux aînés. Le présent article décrit les principaux résultats de l'évaluation d'implantation et de processus. Cette évaluation visait à documenter les activités et fonctions centrales du mécanisme de coordination des services afin de voir dans quelle mesure le modèle implanté et son fonctionnement s'approchent ou non du modèle visé et ce, dans la perspective d'apporter des ajustements qui pourraient s'avérer nécessaires. Les principaux résultats sur la clientèle rejointe, sur les fonctions assumées par l'équipe de gestion de cas et sur l'organisation de travail sont ici abordés et discutés à la lumière d'autres études sur la coordination des soins et des services aux personnes âgées en perte d'autonomie. Des suggestions sont faites en regard de ces résultats et de ceux portant sur l'efficacité et les coûts tirés d'une autre recherche afin d'améliorer l'efficacité et l'efficience de ce modèle de coordination de soins et de services aux aînés. Sans être généralisables d'emblée, plusieurs composantes de ce nouveau modèle pourraient être réutilisées auprès d'autres clientèles.Assessment of the implementation of an innovative experience: network of integrated services for the elderly in the Bois-Franc region Conscious of problems related to coordination of services for the elderly on its territory, the working group on health and social services of the Bois-Francs in the Mauricie and Centre-du-Québec regions implemented in February 1997, after two years of planning, a new coordination model of services for the frail elderly. This model is innovative because it combines the unique entry, case management, individualized services plan as well as the presence of three levels of concertation : strategic, tactical and clinical. The model also has the characteristic of offering comprehensive services to the elderly. This article describes the major results of an assessment of the implementation and process of this model. This assessment aimed at documenting the activities and functions of the coordination mecanism of services in order to see to what extent the model implemented and its functionning is close or not to the one proposed and this, in a perspective of bringing the necessary adjustments. The major results on clientele reached, various functions of a team of case managers and organization of work are discussed in the light of other studies on coordination of services for frail older people. Suggestions regarding these results and those pertaining to efficiency and cost in another study are made in order to improve the efficiency of the model. Many components of this new model could be applied to other clientele.Evaluación de la implantación de una experiencia novedosa: la red integrada de servicios para ancianos de los Bois-Francs Consciente de la existencia de problemas de coordinación de servicios para ancianos de su teritorio, la mesa de concertación de los servicios de salud y de servicios sociales de los Bois-Francs en la región Mauricie y del Centro-del-Québec estableció en febrero 1997, despues de dos años de planificación, un modelo nuevo de coordinación de cuidados y de servicios a los ancianos con perdida de autonomia. Este modelo es novedoso porque combina el portillo único de entrada, la gestión de caso, el plan de servicios individualisados y la presencia de tres niveles de concertación: estrategico, táctico y clínico. Tiene tambien la particularidad de cubrir el continuum de cuidados y de servicios a los ancianos. Este articulo describe los resultados principales de la evaluación y del proceso de establecimiento. Esta evaluación queria documentar las actividades y funciones centrales del mecanismo de coordinación para ver como el modelo establecido y su funcionamiento se acercan o no del modelo previstado a dentro una perspectiva de llevar ajustos si necesario. Los resultados principales sobre la clientela, sobre las funciones asumidas por el equipo de gestión de caso y sobre la organisación del trabajo estan discudidos a la luz de otras investigaciones sobre la coordinación de cuidados y de servicios a personas ancianas en perdida de autonomia. Se hacen sugerencias a la vista de estos resultados y de los apuntados sobre la eficacia y de los costos de otra investigación para mejorar la eficacia de este modelo de coordinación de cuidados y de servicios a los ancianos. Sin ser generalizables de entrada componentes del modelo nuevo podrian ser reutilisadas con otras clientelas.Avaliação da implantação de uma experiência inovadora: rede integrada de serviços aos idosos de Bois-Francs Consciente da existência de problemas relacionados à coordenação dos serviços prestados aos idosos em seu território, a mesa redonda sobre os serviços de saúde e os serviços sociais de Bois-Francs na região de Mauricie e do Centro do Quebec implantou, em fevereiro de 1997, após dois anos de planejamento, um novo modelo de coordenação dos cuidados e serviços prestados às pessoas idosas com perda de autonomia. Este modelo é inovador porque ele inclui o balcão ou a porta de entrada única, a gestão de casos, o plano de serviços individualizado e a presença de três níveis de acordo: estratégia, tática e clínica. Ele também tem a particularidade de englobar todo o processo de cuidados e serviços prestados aos idosos. O presente artigo descreve os principais resultados da avaliação da implantação e do processo. Esta avaliação teve como objetivo documentar as atividades e funções centrais do mecanismo de coordenação dos serviços, para verificar em que medida o modelo implantado e seu funcionamento se aproximam ou não do modelo esperado e estudar as possíveis mudanças necessárias. Os principais resultados obtidos junto a esta clientela, nas funções assumidas pela equipe de gestão de caso e na organização de trabalho, são abordadas aqui e discutidas em relação a outros estudos sobre a coordenação de cuidados e de serviços aos idosos com perda de autonomia. Os autores trazem algumas sugestões com respeito a estes resultados, e aos que tratam sobre a eficácia e os custos, tirados de uma outra pesquisa para melhorar a eficácia e a eficiência deste modelo de coordenação de cuidados e de serviços prestados aos idosos. Sem que este novo modelo possa ser aplicado a todas as circunstâncias, várias de suas características poderiam ser utilizadas junto a outros clientes

More published full-time researchers, early career researchers, clinician-researchers and graduate students unite to call for actions against the pseudoscientific claim that chiropractic care boosts immunity

Letter to the edito

Identifying factors likely to influence compliance with diagnostic imaging guideline recommendations for spine disorders among chiropractors in North America: a focus group study using the Theoretical Domains Framework

Background: The Theoretical Domains Framework (TDF) was developed to investigate determinants of specific clinical behaviors and inform the design of interventions to change professional behavior. This framework was used to explore the beliefs of chiropractors in an American Provider Network and two Canadian provinces about their adherence to evidence-based recommendations for spine radiography for uncomplicated back pain. The primary objective of the study was to identify chiropractors’ beliefs about managing uncomplicated back pain without xrays and to explore barriers and facilitators to implementing evidence-based recommendations on lumbar spine xrays. A secondary objective was to compare chiropractors in the United States and Canada on their beliefs regarding the use of spine x-rays. Methods: Six focus groups exploring beliefs about managing back pain without x-rays were conducted with a purposive sample. The interview guide was based upon the TDF. Focus groups were digitally recorded, transcribed verbatim, and analyzed by two independent assessors using thematic content analysis based on the TDF. Results: Five domains were identified as likely relevant. Key beliefs within these domains included the following: conflicting comments about the potential consequences of not ordering x-rays (risk of missing a pathology, avoiding adverse treatment effects, risks of litigation, determining the treatment plan, and using x-ray-driven techniques contrasted with perceived benefits of minimizing patient radiation exposure and reducing costs; beliefs about consequences); beliefs regarding professional autonomy, professional credibility, lack of standardization, and agreement with guidelines widely varied (social/professional role & identity); the influence of formal training, colleagues, and patients also appeared to be important factors (social influences); conflicting comments regarding levels of confidence and comfort in managing patients without x-rays (belief about capabilities); and guideline awareness and agreements (knowledge). Conclusions: Chiropractors’ use of diagnostic imaging appears to be influenced by a number of factors. Five key domains may be important considering the presence of conflicting beliefs, evidence of strong beliefs likely to impact the behavior of interest, and high frequency of beliefs. The results will inform the development of a theorybased survey to help identify potential targets for behavioral-change strategies

Factors associated with back pain in children aged 6 to 12 years of age, an eight months prospective study

Associated factors of back pain (BP) development before puberty and its persistence are poorly documented. We investigated the association and possible temporality between prior BP history (PBPH), muscular endurance (ME), aerobic capacity (AC), sport activity variables (SAV) and BP in children aged 6 to 12. We collected baseline characteristics (demographics, PBPH, ME, AC and SAV) of children from three primary schools in Canada. Parents replied to weekly text messages regarding their children BP status over an 8-month period. Logistic regression models were adjusted for potential confounders. Data from 242 children (46% female; 8.6 ± 1.7 years) were included. Over the 8-month survey BP prevalence was 48.1%, while the cumulative incidence was 31.9%. The occurrence of at least one BP event was associated with PBPH [OR (IC 95%) = 6.33 (2.35–17.04)] and high AC [2.89 (1.21–6.90)]. High AC was also associated with the development of a first BP episode [2.78 (1.09–7.07)], but ME and SAV were not. BP appears to be relatively common before puberty. BP history seems to be strongly associated with BP recurrence in children. Aerobic capacity is associated with first BP episode development

Nine years of in situ soil warming and topography impact the temperature sensitivity and basal respiration rate of the forest floor in a Canadian boreal forest

The forest floor of boreal forest stores large amounts of organic C that may react to a warming climate and increased N deposition. It is therefore crucial to assess the impact of these factors on the temperature sensitivity of this C pool to help predict future soil CO2 emissions from boreal forest soils to the atmosphere. In this study, soil warming (+2–4°C) and canopy N addition (CNA; +0.30–0.35 kg·N·ha-1·yr-1) were replicated along a topographic gradient (upper, back and lower slope) in a boreal forest in Quebec, Canada. After nine years of treatment, the forest floor was collected in each plot, and its organic C composition was characterized through solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Forest floor samples were incubated at four temperatures (16, 24, 32 and 40°C) and respiration rates (RR) measured to assess the temperature sensitivity of forest floor RR (Q10 = e10k) and basal RR (B). Both soil warming and CNA had no significant effect on forest floor chemistry (e.g., C, N, Ca and Mg content, amount of soil organic matter, pH, chemical functional groups). The NMR analyses did not show evidence of significant changes in the forest floor organic C quality. Nonetheless, a significant effect of soil warming on both the Q10 of RR and B was observed. On average, B was 72% lower and Q10 45% higher in the warmed, versus the control plots. This result implies that forest floor respiration will more strongly react to changes in soil temperature in a future warmer climate. CNA had no significant effect on the measured soil and respiration parameters, and no interaction effects with warming. In contrast, slope position had a significant effect on forest floor organic C quality. Upper slope plots had higher soil alkyl C:O-alkyl C ratios and lower B values than those in the lower slope, across all different treatments. This result likely resulted from a relative decrease in the labile C fraction in the upper slope, characterized by lower moisture levels. Our results point towards higher temperature sensitivity of RR under warmer conditions, accompanied by an overall down-regulation of RR at low temperatures (lower B). Since soil C quantity and quality were unaffected by the nine years of warming, the observed patterns could result from microbial adaptations to warming