Numerical evaluation of convex-roof entanglement measures with applications to spin rings

We present two ready-to-use numerical algorithms to evaluate convex-roof extensions of arbitrary pure-state entanglement monotones. Their implementation leaves the user merely with the task of calculating derivatives of the respective pure-state measure. We provide numerical tests of the algorithms and demonstrate their good convergence properties. We further employ them in order to investigate the entanglement in particular few-spins systems at finite temperature. Namely, we consider ferromagnetic Heisenberg exchange-coupled spin-1/2 rings subject to an inhomogeneous in-plane field geometry obeying full rotational symmetry around the axis perpendicular to the ring through its center. We demonstrate that highly entangled states can be obtained in these systems at sufficiently low temperatures and by tuning the strength of a magnetic field configuration to an optimal value which is identified numerically.Comment: 13 pages, 5 figure

Highly Entangled Ground States in Tripartite Qubit Systems

We investigate the creation of highly entangled ground states in a system of three exchange-coupled qubits arranged in a ring geometry. Suitable magnetic field configurations yielding approximate GHZ and exact W ground states are identified. The entanglement in the system is studied at finite temperature in terms of the mixed-state tangle tau. By adapting a steepest-descent optimization algorithm we demonstrate that tau can be evaluated efficiently and with high precision. We identify the parameter regime for which the equilibrium entanglement of the tripartite system reaches its maximum.Comment: 4 pages, 2 figure

«Le monde a besoin du FiBL»

Bernard Lehmann, ancien chef de l’Office fédéral de l’agriculture, préside le Conseil de fondation du FiBL. Il voit l’Institut comme précurseur pour résoudre des crises

"Le monde a besoin du FiBL"

Bernard Lehmann, ancien chef de l’Office fédéral de l’agriculture, préside le Conseil de fondation du FiBL. Il voit l’Institut comme précurseur pour résoudre des crises

"Il mondo ha bisogno del FiBL"

Bernard Lehmann è stato direttore dell’Ufficio federale dell’agricoltura e presiede ora il consiglio di fondazione del FiBL. Considera l’istituto un apripista per risolvere crisi globali

"Die Welt braucht das FiBL"

Bernard Lehmann war Chef des Bundesamts für Landwirtschaft und präsidiert nun den FiBL-Stiftungsrat. Er sieht das Institut als Schrittmacher bei der Lösung globaler Krisen

Kleine Zecke – Grosse Gefahr

Wir berichten über einen 23-jährigen Patienten, der sich aufgrund persistierender Kopfschmerzen sowie Fieber und Erbrechen in der Hausarztpraxis vorstellte. Im weiteren Verlauf kamen eine rechtsbetonte Tetraparese, eine Dysphagie sowie eine Dysarthrie hinzu und es kam zu einem generalisierten tonisch-klonischen Krampfanfall. Weitere Abklärungen bestätigten eine FSME-Enzephalomyelitis und Polyradikulitis. Auch nach zweimonatiger Rehabilitation blieben beim ungeimpften Patienten sowohl neuropsychologische wie auch fokal-neurologische Residuen bestehen. Schlüsselwörter: FSME, Enzephalomyelitis, Polyradikulitis, Tetraparese. // We report a 23-year-old patient who presented to the general practitioner due to persisting headache, fever, and vomiting. In the further course, a tetraparesis dominated on the right side, dysphagia and dysarthria occurred, and a general tonic-clonic seizure. Further examinations confirmed tick-borne encephalomyelitis as well as polyradiculitis. After two months of rehabilitation, neuropsychological as well as focal-neurological deficits persisted in the unvaccinated patient

Interprofessional and interdisciplinary simulation-based training leads to safe sedation procedures in the emergency department.

BACKGROUND Sedation is a procedure required for many interventions in the Emergency department (ED) such as reductions, surgical procedures or cardioversions. However, especially under emergency conditions with high risk patients and rapidly changing interdisciplinary and interprofessional teams, the procedure caries important risks. It is thus vital but difficult to implement a standard operating procedure for sedation procedures in any ED. Reports on both, implementation strategies as well as their success are currently lacking. This study describes the development, implementation and clinical evaluation of an interprofessional and interdisciplinary simulation-based sedation training concept. METHODS All physicians and nurses with specialised training in emergency medicine at the Berne University Department of Emergency Medicine participated in a mandatory interdisciplinary and interprofessional simulation-based sedation training. The curriculum consisted of an individual self-learning module, an airway skill training course, three simulation-based team training cases, and a final practical learning course in the operating theatre. Before and after each training session, self-efficacy, awareness of emergency procedures, knowledge of sedation medication and crisis resource management were assessed with a questionnaire. Changes in these measures were compared via paired tests, separately for groups formed based on experience and profession. To assess the clinical effect of training, we collected patient and team satisfaction as well as duration and complications for all sedations in the ED within the year after implementation. We further compared time to beginning of procedure, time for duration of procedure and time until discharge after implementation with the one year period before the implementation. Cohen's d was calculated as effect size for all statistically significant tests. RESULTS Fifty staff members (26 nurses and 24 physicians) participated in the training. In all subgroups, there is a significant increase in self-efficacy and knowledge with high effect size (d z  = 1.8). The learning is independent of profession and experience level. In the clinical evaluation after implementation, we found no major complications among the sedations performed. Time to procedure significantly improved after the introduction of the training (d = 0.88). DISCUSSION Learning is independent of previous working experience and equally effective in raising the self-efficacy and knowledge in all professional groups. Clinical outcome evaluation confirms the concepts safety and feasibility. CONCLUSION An interprofessional and interdisciplinary simulation-based sedation training is an efficient way to implement a conscious sedation concept in an ED

libCreme: An optimization library for evaluating convex-roof entanglement measures

We present the software library libCreme which we have previously used to successfully calculate convex-roof entanglement measures of mixed quantum states appearing in realistic physical systems. Evaluating the amount of entanglement in such states is in general a non-trivial task requiring to solve a highly non-linear complex optimization problem. The algorithms provided here are able to achieve to do this for a large and important class of entanglement measures. The library is mostly written in the Matlab programming language, but is fully compatible to the free and open-source Octave platform. Some inefficient subroutines are written in C/C++ for better performance. This manuscript discusses the most important theoretical concepts and workings of the algorithms, focussing on the actual implementation and usage within the library. Detailed examples in the end should make it easy for the user to apply libCreme to specific problems.Comment: 13 pages, 1 figure. The program code can be downloaded either from the CPC Library (http://cpc.cs.qub.ac.uk) or directly at http://quantumtheory.physik.unibas.ch/people/roethlisberger/libCreme.zi