Mid-infrared quantum optics in silicon

Applied quantum optics stands to revolutionise many aspects of information technology, provided performance can be maintained when scaled up. Silicon quantum photonics satisfies the scaling requirements of miniaturisation and manufacturability, but at 1.55 $\mu$m it suffers from unacceptable linear and nonlinear loss. Here we show that, by translating silicon quantum photonics to the mid-infrared, a new quantum optics platform is created which can simultaneously maximise manufacturability and miniaturisation, while minimising loss. We demonstrate the necessary platform components: photon-pair generation, single-photon detection, and high-visibility quantum interference, all at wavelengths beyond 2 $\mu$m. Across various regimes, we observe a maximum net coincidence rate of 448 $\pm$ 12 Hz, a coincidence-to-accidental ratio of 25.7 $\pm$ 1.1, and, a net two photon quantum interference visibility of 0.993 $\pm$ 0.017. Mid-infrared silicon quantum photonics will bring new quantum applications within reach.Comment: 8 pages, 4 figures; revised figures, updated discussion in section 3, typos corrected, added referenc

High-performance, adiabatically nanotapered fibre-chip couplers in silicon at 2 microns wavelength

Fibre optic technology connects the world through the Internet, enables remote sensing, and connects disparate functional optical devices. Highly confined silicon photonics promises extreme scale and functional integration. However, the optical modes of silicon nanowire waveguides and optical fibres are very different, making efficient fibre-chip coupling a challenge. Vertical grating couplers, the dominant coupling method today, have limited optical bandwidth and are naturally out-of-plane. Here we demonstrate a new method that is low-loss, broadband, easily manufacturable, and naturally planar. We adiabatically couple a tapering silicon nanowire waveguide to a conic nanotapered optical fibre, measuring transmission between 2.0 and 2.2 micron wavelength. The silicon chip is fabricated at a commercial foundry and then post-processed to release the tapering nanowires. We estimate an optimal per-coupler transmission of -0.48 dB (maximum; 95% confidence interval [+0.46, -1.68] dB) and a 1-dB bandwidth of 295 nm . With automated measurements, we quantify the device tolerance to lateral misalignment, measuring a flat response within +/- 0.968 micron. This design can enable low-loss modular systems of integrated photonics irrespective of material and waveband.Comment: 6 pages, 3 figure

Patients' Experience of therapeutic footwear whilst living at risk of neuropathic diabetic foot ulceration: an interpretative phenomenological analysis (IPA).

BACKGROUND: Previous work has found that people with diabetes do not wear their therapeutic footwear as directed, but the thinking behind this behaviour is unclear. Adherence to therapeutic footwear advice must improve in order to reduce foot ulceration and amputation risk in people with diabetes and neuropathy. Therefore this study aimed to explore the psychological influences and personal experiences behind the daily footwear selection of individuals with diabetes and neuropathy. METHODS: An interpretative phenomenological analysis (IPA) approach was used to explore the understanding and experience of therapeutic footwear use in people living at risk of diabetic neuropathic foot ulceration. This study benefited from the purposive selection of a small sample of four people and used in-depth semi structured interviews because it facilitated the deep and detailed examination of personal thoughts and feelings behind footwear selection. FINDINGS: Four overlapping themes that interact to regulate footwear choice emerged from the analyses: a) Self-perception dilemma; resolving the balance of risk experienced by people with diabetes and neuropathy day to day, between choosing to wear footwear to look and feel normal and choosing footwear to protect their feet from foot ulceration; b) Reflective adaption; The modification and individualisation of a set of values about footwear usage created in the minds of people with diabetes and neuropathy; c) Adherence response; The realignment of footwear choice with personal values, to reinforce the decision not to change behaviour or bring about increased footwear adherence, with or without appearance management; d) Reality appraisal; A here and now appraisal of the personal benefit of footwear choice on emotional and physical wellbeing, with additional consideration to the preservation of therapeutic footwear. CONCLUSION: For some people living at risk of diabetic neuropathic foot ulceration, the decision whether or not to wear therapeutic footwear is driven by the individual 'here and now', risks and benefits, of footwear choice on emotional and physical well-being for a given social context

Is Experience as a Prisoner of War a Risk Factor for Accelerated Age-Related Illness and Disability?

OBJECTIVE: To determine whether the experience of internment as a Prisoner of War (POW) during World War II was associated with a higher prevalence of chronic disease and diminished functional performance in later life. DESIGN: A retrospective and prospective cohort design. SETTING: Concord Repatriation General Hospital, Sydney, Australia. PARTICIPANTS: A random sample of 101 Australian, male, ex-prisoners of the Japanese and a comparison group of 107 non-POW combatants from the same theatre of war. MEASUREMENTS: Outcome variables were self-perceived health status, hospital admissions and length of stay, number of prescription medications used, number of somatic symptoms reported, number and types of medical diagnoses, a neurology of aging clinical examination, and the Instrumental Activities of Daily Living (IADL) and Physical Self Maintenance Scales (PSMS). RESULTS: Prisoners of War reported more somatic symptoms (mean 7.2 vs 5.4, P = .002) than non-POWs, had more diagnoses (mean 9.4 vs 7.7 P < .001), and used a greater number of different medications (mean 4.5 vs 3.4, P = .001). There were no differences in hospital admissions or length of stay. Among 15 broad categories of diagnosis, differences were confined to gastrointestinal disorders (POWs 63% vs non-POWs 49%, P = .032), musculoskeletal disorders (POWs 76% vs non-POWs 60%, P = .011), and cognitive disorders (excluding head injury, dementia, and stroke) (POWs 31% vs non-POWs 15%, P = .006). Of the 36 signs in the neurology of aging examination, POWs had a significantly higher proportion of seven extrapyramidal signs and six signs relating to ataxia. POWs were more likely to be impaired on the IADL scale than were non-POWs (33% vs 17%, P = .012) but not significantly more likely to be impaired on the PSMS. CONCLUSIONS: There were few differences between POWs and controls, and those differences were relatively small. Our findings do not support a major role for a catastrophic life stress in the development of chronic illness and disability in later life. However it is possible that the POW experience played a part in premature, abnormal, or unsuccessful aging in some individuals