Variational properties of a pumped dynamical system

We have earlier constructed a generalized entropy concept to show the direction of time in an evolution following from a Markov generator. In such a dynamical system, the entity found changes in a monotonic way starting from any initial state of the system. In this paper, we generalize the treatment to the case when population is pumped into the system from levels not explicitly considered. These populations then pass through the coupled levels and exit by decay to levels outside the system. We derive the form of the equation of motion and relate it to our earlier treatments. It turns out that the formalism can be generalized to the new situation. Its physically relevant features are demonstrated, and the behaviour obtained is illustrated by numerical treatment of the standard two-level system with pumping and relaxation included.Comment: 10 pages, 2 figure

Transformations between symmetric sets of quantum states

We investigate probabilistic transformations of quantum states from a `source' set to a `target' set of states. Such transforms have many applications. They can be used for tasks which include state-dependent cloning or quantum state discrimination, and as interfaces between systems whose information encodings are not related by a unitary transform, such as continuous-variable systems and finite-dimensional systems. In a probabilistic transform, information may be lost or leaked, and we explain the concepts of leak and redundancy. Following this, we show how the analysis of probabilistic transforms significantly simplifies for symmetric source and target sets of states. In particular, we give a simple linear program which solves the task of finding optimal transforms, and a method of characterizing the introduced leak and redundancy in information-theoretic terms. Using the developed techniques, we analyse a class of transforms which convert coherent states with information encoded in their relative phase to symmetric qubit states. Each of these sets of states on their own appears in many well studied quantum information protocols. Finally, we suggest an asymptotic realization based on quantum scissors.Comment: 10 pages; 5 figure

The role of outdoor activities in elderly day center facilities during COVID-19 : a qualitative interview study in Stockholms Stad

Denna kvalitativa intervjustudie undersöker utevistelsens roll i äldreomsorgens förebyggande verksamhet under det pandemidrabbade året 2020 samt huruvida den kontext som COVID-19 skapat har gett upphov till nya insikter om utemiljön som framtida resurs. Genom semistrukturerade intervjuer med personal från fem olika stadsdelar i Stockholms Stad samlas erfarenheter som i två resultatdelar visar på En förändrad användning av utemiljön under 2020 och En förändrad syn på framtida användning av utemiljön. Under respektive del identifieras underliggande teman där den förändrade användningen kopplas till utflyttade aktiviteter, fler och nya aktiviteter samt ett behov av variation, en utökad användning av stadsdelsområdet, ökad synlighet, en längre säsong för uteaktivitet och en ny öppenhet till naturen. Utifrån dessa teman kopplas den förändrade synen på utemiljöns framtida användning vidare till en sänkt tröskel för uteaktivitet och ett ökat intresse för uteverksamhet. Dessa teman relateras sedan till Grahns Pyramid av stödjande miljöer där platsegenskaper för en hälsofrämjande stadsdel pekas ut som viktiga sett till den utveckling som resultatet pekar på. Den förändrade användningen av utemiljön tyder på att äldre fått tillfälle att aktivera sig sett till pyramidens olika nivåer. Den utökade användningen av stadsdelsområdet visar en utveckling där utemiljön som arena för förebyggande verksamhet har vuxit. Slutsatsen mynnar således ut i att situationen bidragit till insikter gällande utemiljöns roll, och att detta tillfälle, där vikten av förebyggande arbete och hälsofrämjande åtgärder fått gehör, samt där det identifierats en ny öppenhet och förståelse för naturens hälsofrämjande effekter, är ett tillfälle att ta i akt för att vidare utveckla utevistelsens roll i förebyggande äldreomsorg.This qualitative interview study examines the role of outdoor activities in the preventive operations of elderly care facilities during the COVID-19 pandemic in 2020, searching for experiences that tell whether the context has given rise to new insights about outdoor activities and the outdoor environment. Through semi-structured interviews with staff from five different districts in the City of Stockholm, experience is gathered and displayed in two parts: a changed use of the outdoor environment in 2020 and a changed view of future use of the outdoor environment. Under each part, underlying themes are identified. The changed use in 2020 connects to relocated activities, more and new activities as well as a need for variety, an increased use of the district area, increased visibility, a longer season for outdoor activities and a new openness to nature. Based on these themes, the changed view of the future use of the outdoor environment is linked to a lowered threshold for implementing outdoor activity and an increased interest in outdoor aspects. The analysis then relates these themes to Grahn's Pyramid of supportive environments where health�promoting characteristics are pointed out as important in terms of the development that the themes point towards. Furthermore, the changed use of the outdoor environment indicates that the elderly have had the opportunity to activate themselves at the different levels of the pyramid. Further analysis also links the expanded use of the district area to a development where the outdoor environment as an arena for preventive activities has been expanded. The conclusion thus results in the situation contributing to insights regarding the role of the outdoor environment, where the importance of preventive work and health promotion measures has been heard, and where a new openness and understanding of nature's health promoting effects has been identified, is an opportunity for acting further to develop the role of the outdoor environment in preventive care for the elderly

Smart choices for socially sustainable outdoor environments in residential areas

Syftet med arbetet är i huvudsak att undersöka vilka material-, utrustnings- samt växtval som är hållbara, främst ur sociala och ekonomiska perspektiv, med fokus på dels låga skötselbehov, dels god funktion för alla åldrar i en gemensam bostadsnära utemiljö. Målet är att utforma ett gestaltningsförslag för samfälligheten Ståndskallet i Lund som möter de boendes önskemål och således en bred användargrupp. Gestaltningsförslaget ska, utöver att fungera för en bred användargrupp, ta hänsyn till skötselinsatser och kostnader i de material-, utrustnings- och växtval som görs. I litteraturstudien undersöks till att börja med hur bostadsnära utemiljöer kan utformas utifrån olika användarperspektiv, såväl små barns som äldre vuxnas. Vidare undersöks olika aspekter att ta hänsyn till i de material-, utrustnings- och växtval som görs för att skapa utemiljöer till en relativt låg kostnad och med låga skötselinsatser som samtidigt är miljömässigt fördelaktiga. En enkätundersökning gjordes även där de boende inom samfälligheten Ståndskallet fick svara på ett antal frågor kring önskemål i utemiljön för att en framtida omgestaltning skulle skulle få god funktion för dem. Arbetet resulterade i ett gestaltningsförslag vilket utformades med grund från den information som erhölls genom litteraturstudien och enkätundersökningen. Arbetet visade att det, genom att beakta olika användarperspektiv samt kostnader och användningsområden hos olika material, utrustning och växter, är möjligt att utforma socialt hållbara utemiljöer i bostadsområden med smarta material-, utrustnings-, och växtval.The main purpose of this thesis was to investigate which material, equipment and plant choices are best to facilitate the successful design of common outdoor living areas. The investigation focused on sustainable choices, primarily from a social and economic perspective, and those tha centred on ensuring low maintenance and good function for all ages. The aim was to create a design proposal for the community Ståndskallet in Lund, that meets the residents' wishes and thus a broad user group. The design proposal must, in addition to being suitable for a wide group of users, consider maintenance efforts and costs in the material, equipmentand plant choices that are made. The literature study first examined how residential outdoor environments are best designed to incorporate different user perspectives, from young children to older adults. Furthermore, various aspects were analysed in order to evaluate which material, equipment and plant choices are best to create affordable, low maintenance and environmentally beneficial outdoor environments. Additionally, a survey was conducted where the residents within the community of Ståndskallet had the opportunity to provide their preferences regarding the design of the outdoor environment. This allowed for community buy-in and ensured a transparent design proposal that considered the needs and wishes of all involved. The thesis resulted in a design proposal that was conceived based on the information obtained through the literature and questionnaire survey. The result showed that, by considering different choices concerning user perspectives, costs, materials, equipment and plants, it is possible to design socially sustainable outdoor environments in residential areas with smart material, equipment, and plant choices

Dissolved Organic Matter from a colloidal perspective

Dissolved organic matter (DOM) is considered the most bioavailable fraction of soil, and thus play a key role in the cycling of carbon. Because of its mobility, DOM also forms the connection between terrestrial and aquatic systems, and constitutes an important vector for nutrients and contaminants. DOM is in this thesis operationally defined as the organic matter in an aqueous solution which is not retained upon filtration using a pore size of 0.2μm. This means that DOM is a heterogeneous mixture of different chemical components, ranging in size from small molecules up to colloidal particles of a few hundred nanometres.In this thesis, we have characterised DOM from the molecular to colloidal length scale, using a combination of spectroscopy, microscopy and scattering techniques. The DOM was obtained by extraction of soil from the organiclayer of a boreal spruce forest. We found that the dominant chemical component of DOM was carbohydrates, and that about half of the organic carbon was present in colloidal form. The structure of the DOM colloids depended on the extraction procedure used. Large dense aggregates observed at room temperature and below could be dispersed into smaller components by increasing the temperature or pH. Additionally, we studied the bacterial decomposition of DOM and found that the colloidal fraction remained intact, while small molecules were readily decomposed. We have also assessed interactions between DOM and hematite nanoparticles, using neutron scattering. Here, we found that the low molecular weight fraction of DOM induces charge reversal and aggregation of the hematite particles. Our combined results show that the colloidal fraction of DOM needs to be considered when assessing DOM bioavailability and mobility

Implementation vulnerabilities in general quantum cryptography

Quantum cryptography is information-theoretically secure owing to its solid basis in quantum mechanics. However, generally, initial implementations with practical imperfections might open loopholes, allowing an eavesdropper to compromise the security of a quantum cryptographic system. This has been shown to happen for quantum key distribution (QKD). Here we apply experience from implementation security of QKD to several other quantum cryptographic primitives. We survey quantum digital signatures, quantum secret sharing, source-independent quantum random number generation, quantum secure direct communication, and blind quantum computing. We propose how the eavesdropper could in principle exploit the loopholes to violate assumptions in these protocols, breaking their security properties. Applicable countermeasures are also discussed. It is important to consider potential implementation security issues early in protocol design, to shorten the path to future applications.Comment: 13 pages, 8 figure

Maximum observable correlation for a bipartite quantum system

The maximum observable correlation between the two components of a bipartite quantum system is a property of the joint density operator, and is achieved by making particular measurements on the respective components. For pure states it corresponds to making measurements diagonal in a corresponding Schmidt basis. More generally, it is shown that the maximum correlation may be characterised in terms of a `correlation basis' for the joint density operator, which defines the corresponding (nondegenerate) optimal measurements. The maximum coincidence rate for spin measurements on two-qubit systems is determined to be (1+s)/2, where s is the spectral norm of the spin correlation matrix, and upper bounds are obtained for n-valued measurements on general bipartite systems. It is shown that the maximum coincidence rate is never greater than the computable cross norm measure of entanglement, and a much tighter upper bound is conjectured. Connections with optimal state discrimination and entanglement bounds are briefly discussed.Comment: Revtex, no figure

Constructive role of dissipation for driven coupled bosonic modes

We theoretically investigate a system of two coupled bosonic modes subject to both dissipation and external driving. We show that in the steady state the degree of entanglement between the coupled bosonic modes can be enhanced by dissipation. The non-monotonic dependence of entanglement on the decay rates is observed when the bosonic modes are asymmetrically coupled to their local baths. This counterintuitive result opens a new way to better understand the interplay between noise and coherence in continuous variable systems driven away from equilibrium.Comment: 4.5 pages. Published version (with minor modifications