Chip-based microcavities coupled to NV centers in single crystal diamond

Optical coupling of nitrogen vacancy centers in single-crystal diamond to an on-chip microcavity is demonstrated. The microcavity is fabricated from a hybrid gallium phosphide and diamond material system, and supports whispering gallery mode resonances with spectrometer resolution limited Q > 25000

The effect of cycling using active-passive trainers on spasticity, cardiovascular fitness, function and quality of life in people with moderate to severe Multiple Sclerosis (MS): a feasibility study

Background: Exercise options for those with moderate to high levels of disability are limited. The aim of the study was to evaluate the feasibility of a progressive, four week lower limb cycling programme using active-passive trainers (APT's) on spasticity, cardiovascular fitness, function and quality of life in people with moderate to severe MS. Methods: Participants were in-patients in the Physical Disability Rehabilitation Unit, Queen Elizabeth University Hospital, Glasgow, UK and randomised to APT + usual care or usual care only. The APT group received 30 min of APT (2 min passive warm up, 26 min active cycling, 2 min passive cool down),five days per week for 4 weeks. Outcome measures; Oxygen Uptake Efficiency Slope, Modified Ashworth Scale, Multiple Sclerosis Spasticity Scale, Functional Independence Measure, Timed 25 foot walk test and the MSQOL-54, were taken before and after the intervention period. Symmetry, distance cycled and active participation were also recorded for each cycling session .Results:24 participants were recruited, 15 to the intervention and 9 to the control group. There was a 100% adherence to the intervention and a significant increase in average speed, power output and distance cycled (p< 0.001 for each) over the four weeks. There were no adverse events and both groups improved in average scores for all outcome measures. Conclusions: APT cycling was well tolerated, while the cycling parameters improved it was difficult to separate the effects of the therapy programme and APT cycling. A longer duration, fully powered trial in a community setting is merited

Optical loss and lasing characteristics of high-quality-factor AlGaAs microdisk resonators with embedded quantum dots

Optical characterization of AlGaAs microdisk resonant cavities with a quantum dot active region is presented. Direct passive measurement of the optical loss within AlGaAs microdisk resonant structures embedded with InAs/InGaAs dots-in-a-well (DWELL) is performed using an optical-fiber-based probing technique at a wavelength (lambda~1400 nm) that is red-detuned from the dot emission wavelength (lambda~1200 nm). Measurements in the 1400 nm wavelength band on microdisks of diameter D = 4.5 microns show that these structures support modes with cold-cavity quality factors as high as 360,000. DWELL-containing microdisks are then studied through optical pumping at room temperature. Pulsed lasing at lambda ~ 1200 nm is seen for cavities containing a single layer of InAs dots, with threshold values of ~ 17 microWatts, approaching the estimated material transparency level. Room-temperature continuous wave operation is also observed.Comment: 4 pages, 3 figure

Observation of the dynamic Jahn-Teller effect in the excited states of nitrogen-vacancy centers in diamond

The optical transition linewidth and emission polarization of single nitrogen-vacancy (NV) centers are measured from 5 K to room temperature. Inter-excited state population relaxation is shown to broaden the zero-phonon line and both the relaxation and linewidth are found to follow a T^5 dependence for T up to 100 K. This dependence indicates that the dynamic Jahn-Teller effect is the dominant dephasing mechanism for the NV optical transitions at low temperatures

Experimental demonstration of fiber-accessible metal nanoparticle plasmon waveguides for planar energy guiding and sensing

Experimental evidence of mode-selective evanescent power coupling at telecommunication frequencies with efficiencies up to 75 % from a tapered optical fiber to a carefully designed metal nanoparticle plasmon waveguide is presented. The waveguide consists of a two-dimensional square lattice of lithographically defined Au nanoparticles on an optically thin silicon membrane. The dispersion and attenuation properties of the waveguide are analyzed using the fiber taper. The high efficiency of power transfer into these waveguides solves the coupling problem between conventional optics and plasmonic devices and could lead to the development of highly efficient plasmonic sensors and optical switches.Comment: 1 file, 3 figure

Measuring fluorescence into a nanofiber by observing field quadrature noise

We perform balanced homodyne detection of the electromagnetic field in a single-mode tapered optical nanofiber surrounded by rubidium atoms in a magneto-optical trap. Resonant fluorescence of atoms into the nanofiber mode manifests itself as increased quantum noise of the field quadratures. The autocorrelation function of the homodyne detector's output photocurrent exhibits exponential fall-off with a decay time constant of $26.3\pm 0.6$ ns, which is consistent with the theoretical expectation under our experimental conditions. To our knowledge, this is the first experiment in which fluorescence has been observed and measured by balanced optical homodyne detection

Spirituality, Faith, and Mild Alzheimer\u27s Disease

There is some evidence for a positive association between spirituality, cognitive, and behavioral functioning in people with Alzheimer’s disease (AD). However, to our knowledge there is no published data to date that provides an explanatory model for these findings. Twenty-eight individuals with mild AD received in-depth interviews and measures of cognitive, behavioral, emotional, and spiritual functioning to gain insight into this question in this mixed methods study. Findings revealed that people with mild AD can actively engage in meaningful discussion about how spirituality influences their experience of living with AD; that they remain deeply devoted to a relationship with the transcendent (i.e., God, higher power, spirit) and their spiritual communities; that they value and benefit from the sacred aspects of their day-to-day lives; and that their core spiritual values, beliefs, and practices can be activated to help them adapt to the uncertainty of living with AD. Additionally, persons with AD who are experiencing spiritual struggle tend to experience a greater degree of anxiety, depression, and behavioral changes as compared to those who do not, suggesting that spiritual struggle is a risk factor for poorer outcomes in this population. Implications for future research, clinical practice, and community care are provided including how researchers and clinicians can effectively adapt traditional measures of spirituality for use with this population; the importance of integrating spirituality into the assessment and treatment of people with AD; and the role spiritual communitie