Realization of GHZ States and the GHZ Test via Cavity QED

In this article we discuss the realization of atomic GHZ states involving three-level atoms and we show explicitly how to use this state to perform the GHZ test in which it is possible to decide between local realism theories and quantum mechanics. The experimental realizations proposed makes use of the interaction of Rydberg atoms with a cavity prepared in a coherent state.Comment: 16 pages and 3 figures. submitted to J. Mod. Op

Ge quantum dot arrays grown by ultrahigh vacuum molecular beam epitaxy on the Si(001) surface: nucleation, morphology and CMOS compatibility

Issues of morphology, nucleation and growth of Ge cluster arrays deposited by ultrahigh vacuum molecular beam epitaxy on the Si(001) surface are considered. Difference in nucleation of quantum dots during Ge deposition at low (<600 deg C) and high (>600 deg. C) temperatures is studied by high resolution scanning tunneling microscopy. The atomic models of growth of both species of Ge huts---pyramids and wedges---are proposed. The growth cycle of Ge QD arrays at low temperatures is explored. A problem of lowering of the array formation temperature is discussed with the focus on CMOS compatibility of the entire process; a special attention is paid upon approaches to reduction of treatment temperature during the Si(001) surface pre-growth cleaning, which is at once a key and the highest-temperature phase of the Ge/Si(001) quantum dot dense array formation process. The temperature of the Si clean surface preparation, the final high-temperature step of which is, as a rule, carried out directly in the MBE chamber just before the structure deposition, determines the compatibility of formation process of Ge-QD-array based devices with the CMOS manufacturing cycle. Silicon surface hydrogenation at the final stage of its wet chemical etching during the preliminary cleaning is proposed as a possible way of efficient reduction of the Si wafer pre-growth annealing temperature.Comment: 30 pages, 11 figure

Measuring Individual Material Well-Being Using Multidimensional Indices: An Application Using the Gender and Generation Survey for Russia

This paper suggests a new and comprehensive approach to the assessment of the material well-being at the individual level by constructing a multidimensional index. Using this approach, material well-being is understood as a generic notion that covers a number of different domains, whereas the concept of domain is used to distinguish between different aspects of people’s resources, including income security, basic needs, durables, housing and subjective material well-being. Each dimension is measured independently, using the best indicators available, to generate a score or domain index for each aspect of material well-being. The procedure of re-weighting the indicators within the separate domains enables us to account for the disparity in resources and consumer preferences across different population subgroups. The final domain scores, combined with explicit weighting, are then used to generate a summary material well-being index. The domain indices and the summary material well-being index are validated by exploring their relationships to key socio-economic attributes, which were previously shown to be strongly associated with individual material well-being. The results showed that the summary indices of material well-being are characterized by greater differentiation in relation to such measures, as occupational class and judgments of satisfaction with one’s life. This allows us to conclude that our summary indices capture the latent concept of material well-being better than any of our domain indices used separately. Although the index is constructed using the Russian Gender and Generation Survey data for 2007, the methodological approach that we applied can be easily replicated in other surveys which contain information on several aspects of material well-being

Random-phase approximation and its applications in computational chemistry and materials science

The random-phase approximation (RPA) as an approach for computing the electronic correlation energy is reviewed. After a brief account of its basic concept and historical development, the paper is devoted to the theoretical formulations of RPA, and its applications to realistic systems. With several illustrating applications, we discuss the implications of RPA for computational chemistry and materials science. The computational cost of RPA is also addressed which is critical for its widespread use in future applications. In addition, current correction schemes going beyond RPA and directions of further development will be discussed.Comment: 25 pages, 11 figures, published online in J. Mater. Sci. (2012

The turn of the valve: representing with material models

Many scientific models are representations. Building on Goodman and Elgin’s notion of representation-as we analyse what this claim involves by providing a general definition of what makes something a scientific model, and formulating a novel account of how they represent. We call the result the DEKI account of representation, which offers a complex kind of representation involving an interplay of, denotation, exemplification, keying up of properties, and imputation. Throughout we focus on material models, and we illustrate our claims with the Phillips-Newlyn machine. In the conclusion we suggest that, mutatis mutandis, the DEKI account can be carried over to other kinds of models, notably fictional and mathematical models

Infinitesimal Idealization, Easy Road Nominalism, and Fractional Quantum Statistics

It has been recently debated whether there exists a so-called “easy road” to nominalism. In this essay, I attempt to fill a lacuna in the debate by making a connection with the literature on infinite and infinitesimal idealization in science through an example from mathematical physics that has been largely ignored by philosophers. Specifically, by appealing to John Norton’s distinction between idealization and approximation, I argue that the phenomena of fractional quantum statistics bears negatively on Mary Leng’s proposed path to easy road nominalism, thereby partially defending Mark Colyvan’s claim that there is no easy road to nominalism

Structured lifestyle education for people with Schizophrenia (STEPWISE) : mixed methods process evaluation of a group-based lifestyle education programme to support weight loss in people with schizophrenia

Background STEPWISE is a theory-informed self-management education programme that was co-produced with service users, healthcare professionals and interventionists to support weight loss for people with schizophrenia. We report the process evaluation to inform understanding about the intervention and its effectiveness in a randomised controlled trial (RCT) that evaluated its efficacy. Methods Following the UK Medical Research Council (MRC) Guidelines for developing and evaluating complex interventions, we explored implementation quality. We considered causal mechanisms, unanticipated consequences and contextual factors associated with variation in actual and intended outcomes, and integrated treatment fidelity, using the programme theory and a pipeline logic model. We followed a modified version of Linnan and Steckler’s framework and single case design. Qualitative data from semi-structured telephone interviews with service-users (n = 24), healthcare professionals delivering the intervention (n = 20) and interventionists (n = 7) were triangulated with quantitative process and RCT outcome data and with observations by interventionists, to examine convergence within logic model components. Results Training and course materials were available although lacked co-ordination in some trusts. Healthcare professionals gained knowledge and some contemplated changing their practice to reflect the (facilitative) ‘style’ of delivery. They were often responsible for administrative activities increasing the burden of delivery. Healthcare professionals recognised the need to address antipsychotic-induced weight gain and reported potential value from the intervention (subject to the RCT results). However, some doubted senior management commitment and sustainability post-trial. Service-users found the intervention highly acceptable, especially being in a group of people with similar experiences. Service-users perceived weight loss and lifestyle benefits; however, session attendance varied with 23% (n = 47) attending all group-sessions and 17% (n = 36) attending none. Service-users who lost weight wanted closer monitoring and many healthcare professionals wanted to monitor outcomes (e.g. weight) but it was outside the intervention design. No clinical or cost benefit was demonstrated from the intermediate outcomes (RCT) and any changes in RCT outcomes were not due to the intervention. Conclusions This process evaluation provides a greater understanding of why STEPWISE was unsuccessful in promoting weight loss during the clinical trial. Further research is required to evaluate whether different levels of contact and objective monitoring can support people with schizophrenia to lose weight

Spatiotemporal scaling of North American continental interior wetlands: implications for shorebird conservation

Within interior North America, erratic weather patterns and heterogeneous wetland complexes cause wide spatio-temporal variation in the resources available to migrating shorebirds. Identifying the pattern-generating components of landscape-level resources and the scales at which shorebirds respond to these patterns will better facilitate conservation efforts for these species. We constructed descriptive models that identified weather variables associated with creating the spatio-temporal patterns of shorebird habitat in ten landscapes in north-central Oklahoma. We developed a metric capable of measuring the dynamic composition and configuration of shorebird habitat in the region and used field data to empirically estimate the spatial scale at which shorebirds respond to the amount and configuration of habitat. Precipitation, temperature, solar radiation and wind speed best explained the incidence of wetland habitat, but relationships varied among wetland types. Shorebird occurrence patterns were best explained by habitat density estimates at a 1.5 km scale. This model correctly classified 86 % of shorebird observations. At this scale, when habitat density was low, shorebirds occurred in 5 % of surveyed habitat patches but occurrence reached 60 % when habitat density was high. Our results suggest scale dependence in the habitat-use patterns of migratory shorebirds. We discuss potential implications of our results and how integrating this information into conservation efforts may improve conservation strategies and management practices

Initiating and imaging the coherent surface dynamics of charge carriers in real space

The tip of a scanning tunnelling microscope is an atomic-scale source of electrons and holes. As the injected charge spreads out, it can induce adsorbed molecules to react. By comparing large-scale ‘before' and ‘after' images of an adsorbate covered surface, the spatial extent of the nonlocal manipulation is revealed. Here, we measure the nonlocal manipulation of toluene molecules on the Si(111)-7 × 7 surface at room temperature. Both the range and probability of nonlocal manipulation have a voltage dependence. A region within 5–15 nm of the injection site shows a marked reduction in manipulation. We propose that this region marks the extent of the initial coherent (that is, ballistic) time-dependent evolution of the injected charge carrier. Using scanning tunnelling spectroscopy, we develop a model of this time-dependent expansion of the initially localized hole wavepacket within a particular surface state and deduce a quantum coherence (ballistic) lifetime of ∼10 fs

An exploratory phenomenological study exploring the experiences of people with systemic disease who have undergone lower limb amputation and its impact on their well-being.

Study Design A qualitative study utilising an iterative approach in line with the philosophy of interpretive phenomenology. Background Amputation is a life-changing event accompanied by challenges for the affected person with time-dependent depression often used to quantify its level of impact. There are varied factors that contribute to the occurrence of depression and its persistence. The aim of this study was to explore the experiences over time of people with diabetes and/or peripheral vascular disease following an amputation and the impact on their psychological wellbeing. Objectives To develop an understanding of the experience of living with an amputation and a chronic condition in order to help clinicians identify those in need of counselling support. Methodology 6 participants who had experienced a lower limb amputation associated with peripheral vascular disease/diabetes were interviewed on two occasions (baseline and four months). An Interpretative Phenomenological approach was utilised for both data collection and analysis. Results For these participants, amputation was part of the chronology of their chronic disease. It was the individual’s variable experience of health which impacted on their psychological well-being rather than the length of time since amputation. Conclusion The multivariable experience of amputation means that individually tailored counselling/psychological support is recommended