Ultra-narrow inhomogeneous spectral distribution of telecom-wavelength vanadium centres in isotopically-enriched silicon carbide.

Spin-active quantum emitters have emerged as a leading platform for quantum technologies. However, one of their major limitations is the large spread in optical emission frequencies, which typically extends over tens of GHz. Here, we investigate single V4+ vanadium centres in 4H-SiC, which feature telecom-wavelength emission and a coherent S = 1/2 spin state. We perform spectroscopy on single emitters and report the observation of spin-dependent optical transitions, a key requirement for spin-photon interfaces. By engineering the isotopic composition of the SiC matrix, we reduce the inhomogeneous spectral distribution of different emitters down to 100 MHz, significantly smaller than any other single quantum emitter. Additionally, we tailor the dopant concentration to stabilise the telecom-wavelength V4+ charge state, thereby extending its lifetime by at least two orders of magnitude. These results bolster the prospects for single V emitters in SiC as material nodes in scalable telecom quantum networks.

The happy learner: Effects of academic boredom, burnout, and engagement.

This study aimed to investigate the impact of demographic and contextual variables on boredom in English and mathematics, and to test structural models of boredom, learner burnout, learner engagement, and life satisfaction. Using a cross-sectional survey design and employing a convenience sampling technique, 544 secondary school learners in the Sedibeng District, Gauteng, South Africa, took part in the study. The participants completed the Achievement Emotions Questionnaire - English, the Achievement Emotions Questionnaire - Mathematics, the Schoolwork Engagement Inventory, the School Burnout Inventory, and the Satisfaction with Life Scale. Latent variable modeling was used to test measurement and structural models of boredom, burnout, engagement, and life satisfaction. The indirect effects of boredom on life satisfaction were also computed. The results showed that Afrikaans as the home language, the final mark for English in the previous examination, caregivers that cannot help with English homework, and disliking the English teacher predicted boredom in English. Afrikaans as the home language, marks for mathematics in the previous examination, not having the ability to focus on schoolwork at home, and disliking the mathematics teacher predicted boredom in mathematics. Boredom in mathematics and English resulted in an increase in learner burnout and a decrease in learner engagement. Furthermore, boredom in mathematics and English indirectly affected life satisfaction via learner burnout and engagement.

Meaning in life experienced by parents of children living with diabetes.

In this study, nine parents of children living with well-controlled diabetes participated in semi-structured interviews to explore how they make meaning of living with a child with diabetes. Creating a state of normalcy that incorporates the diabetes care plan, empowering their children to successful transition to independent care, positive relationships with their medical team as well as acquiring and sharing diabetes-related knowledge and skills add to the meaning in life of these parents. Health practitioners should facilitate conversations with parents to help them realise their motivation for adhering to the diabetes care plan.

Free spectral range electrical tuning of a high quality on-chip microcavity.

Reconfigurable photonic circuits have applications ranging from next-generation computer architectures to quantum networks, coherent radar and optical metamaterials. Here, we demonstrate an on-chip high quality microcavity with resonances that can be electrically tuned across a full free spectral range (FSR). FSR tuning allows resonance with any source or emitter, or between any number of networked microcavities. We achieve it by integrating nanoelectronic actuation with strong optomechanical interactions that create a highly geometry-dependent effective refractive index. This allows low voltages and sub-nanowatt power consumption. We demonstrate a basic reconfigurable photonic network, bringing the microcavity into resonance with an arbitrary mode of a microtoroidal optical cavity across a telecommunications fibre link. Our results have applications beyond photonic circuits, including widely tuneable integrated lasers, reconfigurable optical filters for telecommunications and astronomy, and on-chip sensor networks.

High bandwidth on-chip capacitive tuning of microtoroid resonators.

We report on the design, fabrication and characterization of silica microtoroid based cavity opto-electromechanical systems (COEMS). Electrodes patterned onto the microtoroid resonators allow for rapid capacitive tuning of the optical whispering gallery mode resonances while maintaining their ultrahigh quality factor, enabling applications such as efficient radio to optical frequency conversion, optical routing and switching applications.

Effect of quantum nuclear motion on hydrogen bonding.

This work considers how the properties of hydrogen bonded complexes, X-H⋯Y, are modified by the quantum motion of the shared proton. Using a simple two-diabatic state model Hamiltonian, the analysis of the symmetric case, where the donor (X) and acceptor (Y) have the same proton affinity, is carried out. For quantitative comparisons, a parametrization specific to the O-H⋯O complexes is used. The vibrational energy levels of the one-dimensional ground state adiabatic potential of the model are used to make quantitative comparisons with a vast body of condensed phase data, spanning a donor-acceptor separation (R) range of about 2.4-3.0 Å, i.e., from strong to weak hydrogen bonds. The position of the proton (which determines the X-H bond length) and its longitudinal vibrational frequency, along with the isotope effects in both are described quantitatively. An analysis of the secondary geometric isotope effect, using a simple extension of the two-state model, yields an improved agreement of the predicted variation with R of frequency isotope effects. The role of bending modes is also considered: their quantum effects compete with those of the stretching mode for weak to moderate H-bond strengths. In spite of the economy in the parametrization of the model used, it offers key insights into the defining features of H-bonds, and semi-quantitatively captures several trends.