Non-linear optomechanical measurement of mechanical motion

Precision measurement of non-linear observables is an important goal in all facets of quantum optics. This allows measurement-based non-classical state preparation, which has been applied to great success in various physical systems, and provides a route for quantum information processing with otherwise linear interactions. In cavity optomechanics much progress has been made using linear interactions and measurement, but observation of non-linear mechanical degrees-of-freedom remains outstanding. Here we report the observation of displacement-squared thermal motion of a micro-mechanical resonator by exploiting the intrinsic non-linearity of the radiation pressure interaction. Using this measurement we generate bimodal mechanical states of motion with separations and feature sizes well below 100~pm. Future improvements to this approach will allow the preparation of quantum superposition states, which can be used to experimentally explore collapse models of the wavefunction and the potential for mechanical-resonator-based quantum information and metrology applications.Comment: 8 pages, 4 figures, extensive supplementary material available with published versio

Barriers to adherence in adolescents and young adults with cystic fibrosis: a questionnaire study in young patients and their parents

Vibeke Bregnballe1, Peter Oluf Schiøtz1, Kirsten A Boisen2, Tacjana Pressler3, Mikael Thastum4 1Department of Paediatrics, Aarhus University Hospital, Aarhus, Denmark; 2Centre of Adolescent Medicine, University Hospital of Copenhagen, Rigshospitalet, Copenhagen, Denmark; 3Cystic Fibrosis Centre, University Hospital of Copenhagen, Rigshospitalet, Copenhagen, Denmark; 4Department of Psychology, University of Aarhus, Aarhus, Denmark Background: Treatment adherence is crucial in patients with cystic fibrosis, but poor adherence is a problem, especially during adolescence. Identification of barriers to treatment adherence and a better understanding of how context shapes barriers is of great importance in the disease. Adolescent reports of barriers to adherence have been studied, but studies of their parents' experience of such barriers have not yet been carried out. The aim of the present study was to explore barriers to treatment adherence identified by young patients with cystic fibrosis and by their parents. Methods: A questionnaire survey of a cohort of young Danish patients with cystic fibrosis aged 14–25 years and their parents was undertaken. Results: Barriers to treatment adherence were reported by 60% of the patients and by 62% of their parents. Patients and parents agreed that the three most common barriers encountered were lack of time, forgetfulness, and unwillingness to take medication in public. We found a significant positive correlation between reported number of barriers and perceived treatment burden. We also found a statistically significant relationship between the reported number of barriers and treatment adherence. A significant association was found between the number of barriers and the reactions of adolescents/young adults and those of their mothers and fathers, and between the number of barriers and the way the family communicated about cystic fibrosis. Conclusion: The present study showed that the majority of adolescents with cystic fibrosis and their parents experienced barriers to treatment adherence. Agreement between adolescents and their parents regarding the level and types of barriers indicates an opportunity for close cooperation between adolescents, their parents, and health care professionals in overcoming adolescent adherence problems. Keywords: cystic fibrosis, adolescents, parents, barriers, adherenc

Present and future of surface-enhanced Raman scattering

The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article