A two-site Kitaev chain in a two-dimensional electron gas.

Artificial Kitaev chains can be used to engineer Majorana bound states (MBSs) in superconductor-semiconductor hybrids1-4. In this work, we realize a two-site Kitaev chain in a two-dimensional electron gas by coupling two quantum dots through a region proximitized by a superconductor. We demonstrate systematic control over inter-dot couplings through in-plane rotations of the magnetic field and via electrostatic gating of the proximitized region. This allows us to tune the system to sweet spots in parameter space, where robust correlated zero-bias conductance peaks are observed in tunnelling spectroscopy. To study the extent of hybridization between localized MBSs, we probe the evolution of the energy spectrum with magnetic field and estimate the Majorana polarization, an important metric for Majorana-based qubits5,6. The implementation of a Kitaev chain on a scalable and flexible two-dimensional platform provides a realistic path towards more advanced experiments that require manipulation and readout of multiple MBSs.

Phase Asymmetry of Andreev Spectra from Cooper-Pair Momentum.

In analogy to conventional semiconductor diodes, the Josephson diode exhibits superconducting properties that are asymmetric in applied bias. The effect has been investigated in a number of systems recently, and requires a combination of broken time-reversal and inversion symmetries. We demonstrate a dual of the usual Josephson diode effect, a nonreciprocal response of Andreev bound states to a superconducting phase difference across the normal region of a superconductor-normal-superconductor Josephson junction, fabricated using an epitaxial InAs/Al heterostructure. Phase asymmetry of the subgap Andreev spectrum is absent in the absence of in-plane magnetic field and reaches a maximum at 0.15 T applied in the plane of the junction transverse to the current direction. We interpret the phase diode effect in this system as resulting from finite-momentum Cooper pairing due to orbital coupling to the in-plane magnetic field. At higher magnetic fields, we observe a sign reversal of the diode effect that appears together with a reopening of the spectral gap. Within our model, the sign reversal of the diode effect at higher fields is correlated with a topological phase transition that requires Zeeman and spin-orbit interactions in addition to orbital coupling.

Triplet correlations in Cooper pair splitters realized in a two-dimensional electron gas.

Cooper pairs occupy the ground state of superconductors and are typically composed of maximally entangled electrons with opposite spin. In order to study the spin and entanglement properties of these electrons, one must separate them spatially via a process known as Cooper pair splitting (CPS). Here we provide the first demonstration of CPS in a semiconductor two-dimensional electron gas (2DEG). By coupling two quantum dots to a superconductor-semiconductor hybrid region we achieve efficient Cooper pair splitting, and clearly distinguish it from other local and non-local processes. When the spin degeneracy of the dots is lifted, they can be operated as spin-filters to obtain information about the spin of the electrons forming the Cooper pair. Not only do we observe a near perfect splitting of Cooper pairs into opposite-spin electrons (i.e. conventional singlet pairing), but also into equal-spin electrons, thus achieving triplet correlations between the quantum dots. Importantly, the exceptionally large spin-orbit interaction in our 2DEGs results in a strong triplet component, comparable in amplitude to the singlet pairing. The demonstration of CPS in a scalable and flexible platform provides a credible route to study on-chip entanglement and topological superconductivity in the form of artificial Kitaev chains.

Control of Andreev Bound States Using Superconducting Phase Texture.

Andreev bound states with opposite phase-inversion asymmetries are observed in local tunneling spectra at the two ends of a superconductor-semiconductor-superconductor planar Josephson junction in the presence of a perpendicular magnetic field, while the nonlocal spectra remain phase symmetric. Spectral signatures agree with a theoretical model, yielding a physical picture in which phase textures in superconducting leads localize and control the position of Andreev bound states in the junction, demonstrating a simple means of controlling the position and size of Andreev states within a planar junction.

Controlling Andreev Bound States with the Magnetic Vector Potential.

Tunneling spectroscopy measurements are often used to probe the energy spectrum of Andreev bound states (ABSs) in semiconductor-superconductor hybrids. Recently, this spectroscopy technique has been incorporated into planar Josephson junctions (JJs) formed in two-dimensional electron gases, a potential platform to engineer phase-controlled topological superconductivity. Here, we perform ABS spectroscopy at the two ends of planar JJs and study the effects of the magnetic vector potential on the ABS spectrum. We show that the local superconducting phase difference arising from the vector potential is equal in magnitude and opposite in sign at the two ends, in agreement with a model that assumes localized ABSs near the tunnel barriers. Complemented with microscopic simulations, our experiments demonstrate that the local phase difference can be used to estimate the relative position of localized ABSs separated by a few hundred nanometers.

Developing and validating a comprehensive measure of coordination in patient aligned care teams.

BACKGROUND/OBJECTIVE: Despite numerous extant measures assessing context-specific elements of care coordination, we are unaware of any comprehensive, team-based instrument that measures the requisite mechanisms and conditions required to coordinate successfully. In this study we develop and validate the psychometric properties of the Coordination Practices Survey, a context-agnostic measure of coordination for primary care teams. METHODS: Coordination items were developed based on a systematic literature review; items from previously developed scales were adapted and new items were created as needed; all items were refined after subject matter expert review and feedback. We collected data from Primary Care teams drawn from 1200 Veterans Health Administration (VHA) medical centers and outpatient clinics nationwide. 1645 primary care team members from 512 patient aligned care teams in the Veterans Health Administration completed the survey from 2015 to 2016. Psychometric properties were assessed after data collection using Cronbach's alpha, intraclass correlations and multilevel confirmatory factor analysis to assess the factor structure. RESULTS: Our findings confirmed the psychometric properties of two distinguishable subscales of coordination: (a) Accountability and (b) Common Understanding. The within- and between-team latent structure of each subscale exhibited adequate fit to the data, as well as appropriately high Cronbach's alpha and intraclass correlations. There was insufficient variability in responses to the predictability subscale to properly assess its psychometric properties. CONCLUSION: With context-specific validation, our subscales of accountability and common understanding may be used to assess coordination processes in other contexts for both research and operational applications.

Bilinear Magnetoresistance in HgTe Topological Insulator: Opposite Signs at Opposite Surfaces Demonstrated by Gate Control.

Spin-orbit effects appearing in topological insulators (TI) and at Rashba interfaces are currently revolutionizing how we can manipulate spins and have led to several newly discovered effects, from spin-charge interconversion and spin-orbit torques to novel magnetoresistance phenomena. In particular, a puzzling magnetoresistance has been evidenced as bilinear in electric and magnetic fields. Here, we report the observation of bilinear magnetoresistance (BMR) in strained HgTe, a prototypical TI. We show that both the amplitude and sign of this BMR can be tuned by controlling with an electric gate the relative proportions of the opposite contributions of opposite surfaces. At magnetic fields of 1 T, the magnetoresistance is of the order of 1% and has a larger figure of merit than previously measured TIs. We propose a theoretical model giving a quantitative account of our experimental data. This phenomenon, unique to TI, offers novel opportunities to tune their electrical response for spintronics.

InSbAs Two-Dimensional Electron Gases as a Platform for Topological Superconductivity.

Topological superconductivity can be engineered in semiconductors with strong spin-orbit interaction coupled to a superconductor. Experimental advances in this field have often been triggered by the development of new hybrid material systems. Among these, two-dimensional electron gases (2DEGs) are of particular interest due to their inherent design flexibility and scalability. Here, we discuss results on a 2D platform based on a ternary 2DEG (InSbAs) coupled to in situ grown aluminum. The spin-orbit coupling in these 2DEGs can be tuned with the As concentration, reaching values up to 400 meV Å, thus exceeding typical values measured in its binary constituents. In addition to a large Landé g-factor of ∼55 (comparable to that of InSb), we show that the clean superconductor-semiconductor interface leads to a hard induced superconducting gap. Using this new platform, we demonstrate the basic operation of phase-controllable Josephson junctions, superconducting islands, and quasi-1D systems, prototypical device geometries used to study Majorana zero modes.

Motives for Dropout Among Former Junior Elite Caribbean Track and Field Athletes: A Qualitative Investigation.

Anecdotal reports within the Caribbean track and field fraternity have revealed that there is a high level of athlete dropout from competitive sport at the junior-elite level, and a poor transition to senior-elite status. Consequently, this qualitative investigation explored the key motives that may have contributed toward the unsuccessful transitions and ensuing dropout of Caribbean track and field athletes during the junior to senior transition period. Eleven former junior-elite track and field athletes (four males, seven females; Mage = 29, SD ± 4.2 years) from four English-speaking Caribbean islands participated in semi-structured interviews. Following an inductive and deductive thematic analysis, four higher order themes were identified: (1) "there's not enough support"; (2) "felt pressure to make sure I committed"; (3) "it's always competitive here"; and (4) "battle with the injuries." For these former junior-elite Caribbean athletes, the decision on whether to continue within the sport was influenced by a combination of factors, although inadequate financial and organizational support had the most bearing on athletes' decision to drop out during the crucial transition years. Implications for consideration by key stakeholders and policymakers within the region are discussed.

Band Structure Extraction at Hybrid Narrow-Gap Semiconductor-Metal Interfaces.

The design of epitaxial semiconductor-superconductor and semiconductor-metal quantum devices requires a detailed understanding of the interfacial electronic band structure. However, the band alignment of buried interfaces is difficult to predict theoretically and to measure experimentally. This work presents a procedure that allows to reliably determine critical parameters for engineering quantum devices; band offset, band bending profile, and number of occupied quantum well subbands of interfacial accumulation layers at semiconductor-metal interfaces. Soft X-ray angle-resolved photoemission is used to directly measure the quantum well states as well as valence bands and core levels for the InAs(100)/Al interface, an important platform for Majorana-zero-mode based topological qubits, and demonstrate that the fabrication process strongly influences the band offset, which in turn controls the topological phase diagrams. Since the method is transferable to other narrow gap semiconductors, it can be used more generally for engineering semiconductor-metal and semiconductor-superconductor interfaces in gate-tunable superconducting devices.

Impact of the talent development environment on the wellbeing and burnout of Caribbean youth track and field athletes.

This study examined the perceived talent development environment (TDE) of youth track and field athletes within the Caribbean region and explores the relationship with their subjective wellbeing and burnout levels. A sample of 400 Caribbean youth track and field athletes (male = 198, and female = 202; age 13-20 years) participated in this cross-sectional study. Athletes responded to a survey which included the Talent Development Environment Questionnaire (TDEQ-5), the World Health Organization Wellbeing Index (WHO-5) and the Athlete Burnout Questionnaire (ABQ). Structural equation modelling showed that a positive and supportive TDE was associated with better athlete wellbeing and lower athlete burnout. Moreover, gender and hours of training moderated relationships of athletes' perceptions of their development environment with wellbeing and burnout levels respectively. Furthermore, there was a positive association between the support network and athlete wellbeing, while holistic quality preparation was negatively associated with athlete burnout. Development environments perceived as supportive and geared towards a holistic athlete-centred approach were associated with better athlete wellbeing and lower burnout.

Linking ICT Availability Demands to Burnout and Work-Family Conflict: The Roles of Workplace Telepressure and Dispositional Self-Regulation.

The advancement of technology has led to an increasingly permeable boundary between work and off-work time. As such, employees may face pressure to immediately respond to work-related information and communication technology (ICT) messages during off-work time. This study examines the mediating role of workplace telepressure on the relationships between ICT availability demands with burnout and work-family conflict, as well as the moderating effects of self-regulation on these relationships. Data were collected from 185 full-time employees at two time points. Results indicated full support for the moderated mediation model, demonstrating that workplace telepressure mediated the relationships between ICT availability demands and burnout and work-family conflict. Moreover, dispositional self-regulation strengthened the direct effect of ICT availability demands on workplace telepressure and the indirect effects of ICT availability demands on burnout and work-family conflict. Theoretical and practical implications are discussed.

Construct validity and reliability of the Talent Development Environment Questionnaire in Caribbean youth track and field athletes.

Caribbean nations stand to benefit significantly from the potential insights that can be gained from the assessment of their athlete talent development environments; which in turn can lead to the formulation of evidence-based strategies and improvements to their sport development pathways. The principal aim of this study was to examine the psychometric properties of the 25-item TDEQ-5 to determine its validity to assess the development environments of talented youth track and field athletes from six English-speaking Caribbean countries. As a secondary aim, we sought to examine athletes' perceptions of their talent development environment within this context. Confirmatory factor analysis revealed adequate model fit of a re-specified model and good overall internal reliability of the scale, therefore offering support for its use within this context. Furthermore, adequate construct validity and internal reliability was found within three subscales (i.e., communication, holistic quality preparation and support network) with subpar scores within two subscales (i.e., long-term development focus and alignment of expectations). Preliminary findings on athletes' perceptions of their environment revealed key strengths in coaches' long-term development focus and communication, however deficiencies were noted in the accessibility and availability of sport-related support and preparation of athletes. In conclusion, the re-specified TDEQ-5 with 25 items appears to be a reliable and valid measure within the Caribbean context. However, it is recommended that the scale be used with some caution with regard to the interpretation of results for the 'long-term development focus' and 'alignment of expectations' subscales.

Factors Influencing the Early Development of World-Class Caribbean Track and Field Athletes: A Qualitative Investigation.

This qualitative investigation sought to explore through a socio-cultural lens the perceived early training and competition environment, and support network of world-class Caribbean track and field athletes and the influence on their sport engagement and progression during early childhood and adolescence. Sixteen world-class track and field athletes (8 males and 8 females; M age = 29, SD = 5 years) from 6 English-speaking Caribbean islands took part in semi-structured interviews. A thematic analysis was performed on the transcribed data. Three superordinate themes were identified as key factors that influenced the early sporting development of world-class Caribbean athletes: (1) conducive sporting environment, (2) functional social support network, and (3) key organizational input. Findings revealed that perceived high levels of deliberate play activity in childhood (6 - 12 years) and an intense track and field competition culture in adolescence (13 - 20 years) were conducive to the continued engagement and progression of world-class Caribbean track and field athletes at the junior level. Furthermore, world-class athletes perceived themselves to be positively influenced by the support received from their immediate social support network and key organizations during this period. This study showed that a conducive sporting environment coupled with optimal social and organizational support may have encouraged world-class Caribbean athletes to remain engaged in track and field and to successfully progress within the sport at the junior level. Findings shed light on the sporting culture at the junior level within the Caribbean region and provide insight into key environmental factors that can influence and foster the development of future World Champions and Olympians.

Ballistic superconductivity and tunable π-junctions in InSb quantum wells.

Planar Josephson junctions (JJs) made in semiconductor quantum wells with large spin-orbit coupling are capable of hosting topological superconductivity. Indium antimonide (InSb) two-dimensional electron gases (2DEGs) are particularly suited for this due to their large Landé g-factor and high carrier mobility, however superconducting hybrids in these 2DEGs remain unexplored. Here we create JJs in high quality InSb 2DEGs and provide evidence of ballistic superconductivity over micron-scale lengths. A Zeeman field produces distinct revivals of the supercurrent in the junction, associated with a 0-π transition. We show that these transitions can be controlled by device design, and tuned in-situ using gates. A comparison between experiments and the theory of ballistic π-Josephson junctions gives excellent quantitative agreement. Our results therefore establish InSb quantum wells as a promising new material platform to study the interplay between superconductivity, spin-orbit interaction and magnetism.

Evidence of topological superconductivity in planar Josephson junctions.

Majorana zero modes-quasiparticle states localized at the boundaries of topological superconductors-are expected to be ideal building blocks for fault-tolerant quantum computing1,2. Several observations of zero-bias conductance peaks measured by tunnelling spectroscopy above a critical magnetic field have been reported as experimental indications of Majorana zero modes in superconductor-semiconductor nanowires3-8. On the other hand, two-dimensional systems offer the alternative approach of confining Majorana channels within planar Josephson junctions, in which the phase difference φ between the superconducting leads represents an additional tuning knob that is predicted to drive the system into the topological phase at lower magnetic fields than for a system without phase bias9,10. Here we report the observation of phase-dependent zero-bias conductance peaks measured by tunnelling spectroscopy at the end of Josephson junctions realized on a heterostructure consisting of aluminium on indium arsenide. Biasing the junction to φ ≈ π reduces the critical field at which the zero-bias peak appears, with respect to φ = 0. The phase and magnetic-field dependence of the zero-energy states is consistent with a model of Majorana zero modes in finite-size Josephson junctions. As well as providing experimental evidence of phase-tuned topological superconductivity, our devices are compatible with superconducting quantum electrodynamics architectures11 and are scalable to the complex geometries needed for topological quantum computing9,12,13.

When work-family conflict hits home: Parental work-family conflict and child health.

Work-family conflict affects employee performance and well-being. However, despite the underlying focus of work-family research on family health and well-being, we have limited knowledge about the impact of role-based stressors, such as work-family conflict, on child health. In this study, we propose and test the stressor-self-regulatory resources-crossover framework. In the spirit of extension of existing work-family research to other cultural settings, we report on two multisource studies conducted in Nigeria to explain whether, how, why, and when parental work-family conflict relates to child health. In Study 1, we collected multisource data from parent-child pairs in low-income families to test whether parental self-regulatory resources explain why work- family conflict relates to child health, resulting in findings that support the stressor-self-regulatory resources-crossover framework. In order to identify possible targets for future organizational-based interventions, we collected Study 2 data from parents and their children (who were enrolled at private schools) to test whether job autonomy and job demands altered the relationship between parental self-regulatory resources and child health. Moderator analyses of the multisource data reveal that self-regulatory resources matter for child health only when job demands are high or when job autonomy is low, pointing to potential intervention and policy levers. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Superconducting gatemon qubit based on a proximitized two-dimensional electron gas.

The coherent tunnelling of Cooper pairs across Josephson junctions (JJs) generates a nonlinear inductance that is used extensively in quantum information processors based on superconducting circuits, from setting qubit transition frequencies1 and interqubit coupling strengths2 to the gain of parametric amplifiers3 for quantum-limited readout. The inductance is either set by tailoring the metal oxide dimensions of single JJs, or magnetically tuned by parallelizing multiple JJs in superconducting quantum interference devices with local current-biased flux lines. JJs based on superconductor-semiconductor hybrids represent a tantalizing all-electric alternative. The gatemon is a recently developed transmon variant that employs locally gated nanowire superconductor-semiconductor JJs for qubit control4,5. Here we go beyond proof-of-concept and demonstrate that semiconducting channels etched from a wafer-scale two-dimensional electron gas (2DEG) are a suitable platform for building a scalable gatemon-based quantum computer. We show that 2DEG gatemons meet the requirements6 by performing voltage-controlled single qubit rotations and two-qubit swap operations. We measure qubit coherence times up to ~2 µs, limited by dielectric loss in the 2DEG substrate.

Identifying job characteristics related to employed women's breastfeeding behaviors.

For employed mothers of infants, reconciliation of work demands and breastfeeding constitutes a significant challenge. The discontinuation of breastfeeding has the potential to result in negative outcomes for the mother (e.g., higher likelihood of obesity), her employer (e.g., increased absenteeism), and her infant (e.g., increased risk of infection). Given previous research findings identifying return to work as a major risk factor for breastfeeding cessation, we investigate what types of job characteristics relate to women's intentions to breastfeed shortly after giving birth and women's actual breastfeeding initiation and duration. Using job titles and job descriptors contained in a large Australian longitudinal cohort data set (N = 809), we coded job titles using the U.S. Department of Labor (DOL)'s Occupational Information Network (O*NET) database and extracted job characteristics. Hazardous working conditions and job autonomy were identified as significant determinants of women's breastfeeding intentions, their initiation of breastfeeding, and ultimately their breastfeeding continuation. Hence, we recommend that human resource professionals, managers, and public health initiatives provide breastfeeding-supportive resources to women who, based on their job characteristics, are at high risk to prematurely discontinue breastfeeding to ensure these mothers have equal opportunity to reap the benefits of breastfeeding. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

A Systematic Literature Review of Instruments to Measure Coordination.

EXECUTIVE SUMMARY: Organizing patient care and improving team coordination have been identified by the Institute of Medicine and the Agency for Healthcare Research and Quality as essential components of high-quality care. Research is lacking, however, on the measurement of care team coordination and its mechanisms. Using an organizational psychology framework developed by Okhuysen and Bechky (O&B) as a guide, the authors identify strengths and gaps in the existing literature related to the measurement of coordination and its associated constructs. The authors conducted a review of peer-reviewed articles in healthcare, management, and psychology journals that contain survey items that could be used to measure the domains in the O&B framework. An initial search yielded 468 articles published from 1978 to 2014, 37 of which came from healthcare journals. From this set, 1,401 candidate survey items were extracted from 74 articles. Of these, 279 items were categorized into at least one O&B domain. Retained items were drawn from scales representing 51 constructs related to teamwork, roles, trust, coordination broadly, and ancillary constructs. Two constructs, physical proximity and plans and rules, were directly represented both in the O&B framework and as standalone constructs in the literature. The remaining constructs contributed items that indirectly assess components of the O&B framework domains. Despite decades of research on coordination, valid survey items for measuring the mechanisms and integrating conditions described by the O&B framework as leading to successful team coordination are scarce, and virtually nonexistent in healthcare, as measures of care team coordination.