Nonlinear optomechanical paddle nanocavities

Nonlinear optomechanical coupling is the basis for many potential future experiments in quantum optomechanics (e.g., quantum non-demolition measurements, preparation of non-classical states), which to date have been difficult to realize due to small non-linearity in typical optomechanical devices. Here we introduce an optomechanical system combining strong nonlinear optomechanical coupling, low mass and large optical mode spacing. This nanoscale "paddle nanocavity" supports mechanical resonances with hundreds of fg mass which couple nonlinearly to optical modes with a quadratic optomechanical coupling coefficient $g^{(2)} > 2\pi\times400$ MHz/nm$^2$, and a two phonon to single photon optomechanical coupling rate $\Delta \omega_0 > 2\pi\times 16$ Hz. This coupling relies on strong phonon-photon interactions in a structure whose optical mode spectrum is highly non--degenerate. Nonlinear optomechanical readout of thermally driven motion in these devices should be observable for T $> 50$ mK, and measurement of phonon shot noise is achievable. This shows that strong nonlinear effects can be realized without relying on coupling between nearly degenerate optical modes, thus avoiding parasitic linear coupling present in two mode systems.Comment: 8 pages, 5 figure

The potential therapeutic benefits of reading poetry to nursing home residents : the road less travelled?

In this paper we report on a project to take poetry into a nursing home, building on the widely-held belief in the benefits of poetry in therapeutic settings. This intervention involved us reading poetry aloud in a nursing home and reflecting on how residents reacted to these texts. Our findings suggest that talking about the poetry allowed members of this community to self-reflect and tell narratives that were important to them. Sometimes the poem served as a catalyst, encouraging the disclosure of poignant stories, while at other times the poems seemed incidental to the stories told by the group. Our subsequent reflections also suggested to us that there were several areas that needed further exploration. The poems are not delivered straight to the listener with no mediation; rather, the poems and the discussion afterwards are mediated by both the general expectations and particular interventions of the audience and the facilitators

Design and experimental demonstration of optomechanical paddle nanocavities

We present the design, fabrication and initial characterization of a paddle nanocavity consisting of a suspended sub-picogram nanomechanical resonator optomechanically coupled to a photonic crystal nanocavity. The optical and mechanical properties of the paddle nanocavity can be systematically designed and optimized, and key characteristics including mechanical frequency easily tailored. Measurements under ambient conditions of a silicon paddle nanocavity demonstrate an optical mode with quality factor $Q_o$ ~ 6000 near 1550 nm, and optomechanical coupling to several mechanical resonances with frequencies $\omega_m/2\pi$ ~ 12-64 MHz, effective masses $m_\text{eff}$ ~ 350-650 fg, and mechanical quality factors $Q_m$ ~ 44-327. Paddle nanocavities are promising for optomechanical sensing and nonlinear optomechanics experiments.Comment: 5 pages, 4 figure

Public preferences and willingness to pay for forest disease control in the UK

Invasive pests and diseases in trees impose a range of costs on society related to reductions in timber values, impacts on recreational opportunities and effects on forest biodiversity. These costs need to be considered when assessing control options and developing public policy. We investigate the preferences and willingness to pay of the UK general public for a range of forest disease control measures using a choice experiment with a sample of 605 people. Respondents were relatively well informed about general tree disease-related issues, such as causes and general measures to minimise the risk of disease spread. They were less knowledgeable about specific tree diseases, with Dutch elm disease and chalara ash dieback being the most well known. We find that disease control programmes in publicly-owned forests and forests owned by charitable trusts are more likely to be supported by the public than equivalent control programmes in privately-owned and/or commercial forests. The nature of scientific uncertainty about diseases does not affect peoples’ preferences for disease control measures significantly. Higher respondent income, greater ex-ante knowledge about tree diseases, and more frequent visits to forests are correlated with greater willingness to support publicly-funded tree disease control programmes in forests. Better knowledge about tree diseases also improves the clarity of respondents’ choices. We find a negative sentiment against some disease control measures, such as clear felling of a forest, and chemical or biocide spraying. We conclude that there is significant public support for part-financing forest disease control policies in the UK, but that this is conditional on forest ownership and the type of control measures used

Dissipative and Dispersive Optomechanics in a Nanocavity Torque Sensor

Dissipative and dispersive optomechanical couplings are experimentally observed in a photonic crystal split-beam nanocavity optimized for detecting nanoscale sources of torque. Dissipative coupling of up to approximately $500$ MHz/nm and dispersive coupling of $2$ GHz/nm enable measurements of sub-pg torsional and cantilever-like mechanical resonances with a thermally-limited torque detection sensitivity of 1.2$\times 10^{-20} \text{N} \, \text{m}/\sqrt{\text{Hz}}$ in ambient conditions and 1.3$\times 10^{-21} \text{N} \, \text{m}/\sqrt{\text{Hz}}$ in low vacuum. Interference between optomechanical coupling mechanisms is observed to enhance detection sensitivity and generate a mechanical-mode-dependent optomechanical wavelength response.Comment: 11 pages, 6 figure

Realism, reflection and responsibility: The challenge of writing effective scenarios to support the development of ethical thinking skills

This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Further and Higher Education on 07/08/2017, available online: http://www.tandfonline.com/doi/abs/10.1080/0309877X.2017.1356915Universities are paying increased attention to how they might support the ethical development of their students as one of a range of graduate attributes that will enable them to negotiate increasingly complex professional, civic and personal futures. Scenario-based learning (SBL) is a longstanding strategy used in ethical teaching and this paper describes and evaluates a version of this approach as applied to a second year undergraduate tutorials module. A quantitative assessment of the development of students’ ethical sensitivity over the course of two deliveries of the module shows an uneven impact but also some encouraging trends. A detailed qualitative analysis of how students responded to each scenario identifies five factors that appear to precipitate more in-depth reflection on ethical problems, and these are presented as useful points of guidance for teachers writing ethical scenarios for the first time or for those aiming to hone their existing practice. These factors include the challenge of devising circumstances which appear realistic and plausible to contemporary undergraduate students, constructing scenarios which encourage readers to reflect on and test their personal values, and portraying events which push students to intervene proactively and so taking individual responsibility for their decisions and actions