Solid-state single-photon sources: recent advances for novel quantum materials

In this review, we describe the current landscape of emergent quantum materials for quantum photonic applications. We focus on three specific solid-state platforms: single emitters in monolayers of transition metal dichalcogenides, defects in hexagonal boron nitride, and colloidal quantum dots in perovskites. These platforms share a unique technological accessibility, enabling the rapid implementation of testbed quantum applications, all while being on the verge of becoming technologically mature enough for a first generation of real-world quantum applications. The review begins with a comprehensive overview of the current state-of-the-art for relevant single-photon sources in the solid-state, introducing the most important performance criteria and experimental characterization techniques along the way. We then benchmark progress for each of the three novel materials against more established (yet complex) platforms, highlighting performance, material-specific advantages, and giving an outlook on quantum applications. This review will thus provide the reader with a snapshot on latest developments in the fast-paced field of emergent single-photon sources in the solid-state, including all the required concepts and experiments relevant to this technology.Comment: 35 pages, 8 figures, review pape

Multipartite entanglement in the photon number basis by sequential excitation of a three-level system

We propose a general scheme to generate entanglement encoded in the photon number basis, via a sequential resonant two-photon excitation of a three-level system. We apply it to the specific case of a quantum dot three-level system, which can emit a photon pair through a biexciton-exciton cascade. The state generated in our scheme constitutes a tool for secure communication, as the multipartite correlations present in the produced state may provide an enhanced rate of secret communication with respect to a perfect GHZ state.Comment: 04 pages and 04 figures. Comments are welcom

Pitfalls in the normalization of real-time polymerase chain reaction data

Real-time polymerase chain reaction (PCR) is commonly used for a sensitive and specific quantification of messenger RNA (mRNA). The levels of mRNA are frequently compared between two or more experimental groups. However, such comparisons require normalization procedures, and reference genes are frequently used for this purpose. We discuss pitfalls in normalization and specifically in the choice of reference genes. Reference genes, which prove suitable for some experimental conditions, are not necessarily similarly appropriate for others. Therefore,a proper validation of the suitability of a given reference gene or sets thereof is required for each experimental setting. Several computer programmes are available to aid such validation

Spider silk gut: Development and characterization of a novel strong spider silk fiber

Spider silk fibers were produced through an alternative processing route that differs widely from natural spinning. The process follows a procedure traditionally used to obtain fibers directly from the glands of silkworms and requires exposure to an acid environment and subsequent stretching. The microstructure and mechanical behavior of the so-called spider silk gut fibers can be tailored to concur with those observed in naturally spun spider silk, except for effects related with the much larger cross-sectional area of the former. In particular spider silk gut has a proper ground state to which the material can revert independently from its previous loading history by supercontraction. A larger cross-sectional area implies that spider silk gut outperforms the natural material in terms of the loads that the fiber can sustain. This property suggests that it could substitute conventional spider silk fibers in some intended uses, such as sutures and scaffolds in tissue engineering.Ministerio de Economía y Competitividad (España) MAT2012-38412-C02-01Fondo Nacional de Ciencias Naturales de China 31160420, 31060282, 30760041Programa de Formación de Jóvenes Científicos (JingGang Star) 20133BCB2302

Quantum interferences and gates with emitter-based coherent photon sources

Quantum emitters, such as atoms, defects in crystals, or quantum dots, are excellent sources of indistinguishable single-photons for quantum technologies. Upon coherent excitation, however, the emitted photonic state includes a vacuum component in a quantum superposition with the one-photon component. This feature has so far been largely disregarded in the framework of linear optical computing. Here we experimentally and theoretically study how the presence of photon-number coherence alters the foundation of photon-photon gates: the Hong-Ou-Mandel interference. We show that the presence of vacuum coherence not only introduces errors to standard photon indistinguishability measurements, but also results in complex quantum interference phenomena. These phenomena lead to additional entanglement that has profound impact on linear computing schemes, as we illustrate by simulating a heralded gate. Our work reveals the rich physics arising from photon-number coherence, which holds the potential to become an asset in future quantum protocols.Comment: 15 pages, 8 figure

Ageism and nursing students, past or reality?: a systematic review

Objective: This systematic review aimed to summarise and update existing knowledge about ageism among nursing students through the following research question: what is the perception and attitudes of ageism among student nurses? Design: A systematic review of longitudinal and cross-sectional studies of ageism in nursing students was carried out. Data sources: The literature search was conducted in the scientific databases Pubmed and Scopus in February 2021. Review methods: After the screening process, 22 studies meeting the selection criteria were selected; 8 more were identified after manually searching the selected paper' reference lists. A total of 30 studies were included in the review. The JBI Critical Appraisal Checklists for Analytical Cross-Sectional studies and for Cohort Studies were used to appraise the articles' quality. Results: There was large variability in the manifestation of ageism among student nurses, as well as in the instruments used for assessment. Most of the articles analysed attitudes towards old age, the majority of which were positive. Being a female student, being on the final year of study and having regular contact or cohabitation with an older adult were three of the main determinants in the expression of positive attitudes towards the elderly. Conclusions: Our findings suggest that student nurses generally have positive attitudes towards old age, although ageist beliefs and discriminatory behaviours were identified and should be studied in greater depth. Training programs for future care professionals have a responsibility to educate from a non-stereotypical perspective based on current societal needs

Prevalence of Symptomatic and Asymptomatic Peripheral Arterial Disease and the Value of the Ankle-brachial Index to Stratify Cardiovascular Risk

AbstractObjectivesTo determine the prevalence of ankle-brachial index (ABI)<0.9 and symptomatic peripheral arterial disease (PAD), association with cardiovascular risk factors (CVRF), and impact of adding ABI measurement to coronary heart disease (CHD) risk screening.DesignPopulation-based cross-sectional survey of 6262 participants aged 35–79 in Girona, Spain.MethodsStandardized measurements (CVRF, ABI, 10-year CHD risk) and history of intermittent claudication (IC), CHD, and stroke were recorded. ABI<0.9 was considered equivalent to moderate-to-high CHD risk (≥10%).ResultsABI<0.9 prevalence was 4.5%. Only 0.62% presented low ABI and IC. Age, current smoker, cardiovascular disease, and uncontrolled hypertension independently associated with ABI<0.9 in both sexes; IC was also associated in men and diabetes in women. Among participants 35–74 free of cardiovascular disease, 6.1% showed moderate-to-high 10-year CHD risk; adding ABI measurement yielded 8.7%. Conversely, the risk function identified 16.8% of these participants as having 10-year CHD risk>10%. In participants 75–79 free of cardiovascular disease, the prevalence of ABI<0.9 (i.e., CHD risk≥10%) was 11.9%.ConclusionsABI<0.9 is relatively frequent in those 35–79, particularly over 74. However, IC and CHD risk≥10% indicators are often missing. Adding ABI measurement to CHD-risk screening better identifies moderate-to-high cardiovascular risk patients