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Abstract Virtually noiseless due to the scarcity of spinful nuclei in the lattice, simple oxides hold promise as hosts of solid-state spin qubits. However, no suitable spin defect has yet been found in these systems. Using high-throughput first-principles calculations, we predict spin defects in calcium oxide with electronic properties remarkably similar to those of the NV center in diamond. These defects are charged complexes where a dopant atom — Sb, Bi, or I — occupies the volume vacated by adjacent cation and anion vacancies. The predicted zero phonon line shows that the Bi complex emits in the telecommunication range, and the computed many-body energy levels suggest a viable optical cycle required for qubit initialization. Notably, the high-spin nucleus of each dopant strongly couples to the electron spin, leading to many controllable quantum levels and the emergence of atomic clock-like transitions that are well protected from environmental noise. Specifically, the Hanh-echo coherence time increases beyond seconds at the clock-like transition in the defect with 209Bi. Our results pave the way to designing quantum states with long coherence times in simple oxides, making them attractive platforms for quantum technologies.

Since the qubit’s performance of solid-state spin centers depends highly on the host material, spin centers using new host materials may offer new qubit applications. We investigate the optical properties of Ce-implanted MgO and MgAl _2 O _4 as potential materials holding the optically accessible qubit. We find that the photoluminescence of Ce-implanted MgAl _2 O _4 is more than 10 times brighter than that of Ce-implanted MgO and observe polarization-dependent emission of Ce center in MgAl _2 O _4 with 2% at 4 K under 500 mT, suggesting that the properties required for initializing and reading the state of the spin qubit have been achieved.

Resonant inelastic x-ray scattering (RIXS) is a powerful spectroscopic technique that offers an elemental- and orbital-selective probe of the electronic excitations over a huge energy range. We present a many-body approach to determine RIXS spectra in solids, yielding an intuitive expression for the RIXS cross section in terms of pathways between intermediate many-body states containing a core hole, and final many-body states containing a valence hole. Explicit excited many-body states are obtained from the diagonalization of the Bethe-Salpeter equation in an all-electron framework. For the paradigmatic example of the fluorine K edge of LiF, we show how the excitation pathways determine the spectral shape of the emission, and demonstrate the nontrivial role of electron-hole correlation in the RIXS spectra.

Sandra Jobke1, Erich Kasten2, Christian Vorwerk31Institute of Medical Psychology, 3Department of Ophthalmology, Otto-von Guericke-University of Magdeburg, Magdeburg, Germany; 2Institute of Medical Psychology, University Hospital Schleswig-Holstein, Luebeck, GermanyPurpose: The prevalence rates of myopia vary between 5% in Australian Aborigines to 84% in Hong Kong and Taiwan, 30% in Norwegian adults, and 49.5% in Swedish schoolchildren. The aim of this study was to determine the prevalence of refractive errors in German children, adolescents, and adults.Methods: The parents (aged 24–65 years) and their children (516 subjects aged 2–35 years) were asked to fill out a questionnaire about their refractive error and spectacle use. Emmetropia was defined as refractive status between +0.25D and –0.25D. Myopia was characterized as ≤−0.5D and hyperopia as ≥+0.5D. All information concerning refractive error were controlled by asking their opticians.Results: The prevalence rates of myopia differed significantly between all investigated age groups: it was 0% in children aged 2–6 years, 5.5% in children aged 7–11 years, 21.0% in adolescents (aged 12–17 years) and 41.3% in adults aged 18–35 years (Pearson’s Chi-square, p = 0.000). Furthermore, 9.8% of children aged 2–6 years were hyperopic, 6.4% of children aged 7–11 years, 3.7% of adolescents, and 2.9% of adults (p = 0.380). The prevalence of myopia in females (23.6%) was significantly higher than in males (14.6%, p = 0.018). The difference between the self-reported and the refractive error reported by their opticians was very small and was not significant (p = 0.850).Conclusion: In Germany, the prevalence of myopia seems to be somewhat lower than in Asia and Europe. There are few comparable studies concerning the prevalence rates of hyperopia.Keywords: Germany, hyperopia, incidence, myopia, prevalence