Cascaded exciton emission of an individual strain-induced quantum dot

Single strain-induced quantum dots are isolated for optical experiments by selective removal of the inducing InP islands from the sample surface. Unpolarized emission of single, bi- and triexciton transitions are identified by power-dependent photoluminescence spectroscopy. Employing time-resolved experiments performed at different excitation powers we find a pronounced shift of the rise and decay times of these different transitions as expected from cascaded emission. Good agreement is found for a rate equation model for a three step cascade

Initial risk matrix, home resources, ability development and children’s achievement

This paper investigates the development of basic cognitive, motor and noncognitive abilities from infancy to adolescence. We analyse the predictive power of these abilities, initial risk conditions and home resources for children’s achievement. Our data are taken from the Mannheim Study of Children at Risk (MARS), an epidemiological cohort study, which follows the long-term outcome of early risk factors. Results indicate that differences in abilities increase during childhood, while there is a remarkable stability in the distribution of the economic and socio-emotional home resources during childhood. Initial risk conditions trigger a cumulative effect. Cognitive, motor and noncognitive abilities acquired during preschool age contribute to the prediction of children’s achievement at school age

Psychisch auffällige Eltern: Risiken für die kindliche Entwicklung im Säuglings- und Kleinkindalter?

'Im Rahmen einer prospektiven Längsschnittstudie an 354 Familien und ihren erstgeborenen Kindern im Alter von 3 und 24 Monaten wird die Rolle psychischer Störungen der Eltern als Risikofaktor für die frühe kindliche Entwicklung untersucht. Die Ergebnisse zeigen, daß Kinder psychisch auffälliger Eltern im Alter von zwei Jahren vor allem sprachlich weniger weit entwickelt und in ihrem Sozialverhalten auffälliger sind als Kinder unauffälliger Eltern. Obwohl die psychische Auffälligkeit eines Elternteils mit zahlreichen anderen Problemen in der Familie konfundiert ist, läßt sich demonstrieren, daß sie einen spezifischen Einfluß auf die kindliche Entwicklung besitzt. Als vermittelnder Faktor zwischen elterlichen Auffälligkeiten und kindlichen Entwicklungsstörungen können gestörte Eltern-Kind-Beziehungen identifiziert werden. Nicht nur das seelische Befinden der Eltern beeinflußt die kindliche Entwicklung, elterliche Erfahrungen im Umgang mit ihren Kindern wirken sich umgekehrt auch auf die psychische Gesundheit der Eltern aus.' (Autorenreferat

All-electron ab-initio\mathrm{\textit{ab-initio}} hyperfine coupling of Si-, Ge- and Sn-vacancy defects in diamond

Colour centres in diamond are attractive candidates for numerous quantum applications due to their good optical properties and long spin coherence times. They also provide access to the even longer coherence of hyperfine coupled nuclear spins in their environment. While the NV centre is well studied, both in experiment and theory, the hyperfine couplings in the more novel centres (SiV, GeV, and SnV) are still largely unknown. Here we report on the first all-electron \textit{ab-initio} calculations of the hyperfine constants for SiV, GeV, and SnV defects in diamond, both for the respective defect atoms ($^{29}$Si, $^{73}$Ge, $^{117}$Sn, $^{119}$Sn), as well as for the surrounding $^{13}$C atoms. Furthermore, we calculate the nuclear quadrupole moments of the GeV defect. We vary the Hartree-Fock mixing parameter for Perdew-Burke-Ernzerhof (PBE) exchange correlation functional and show that the hyperfine couplings of the defect atoms have a linear dependence on the mixing percentage. We calculate the inverse dielectric constant to predict an \textit{ab-initio} mixing percentage. The final hyperfine coupling predictions are close to the experimental values available in the literature. Our results will help to guide future novel experiments on these defects.Comment: 8 pages, 3 figures. Supplementary data (Tables S1-S12) in sourc

Integrated silicon qubit platform with single-spin addressability, exchange control and robust single-shot singlet-triplet readout

Silicon quantum dot spin qubits provide a promising platform for large-scale quantum computation because of their compatibility with conventional CMOS manufacturing and the long coherence times accessible using $^{28}$Si enriched material. A scalable error-corrected quantum processor, however, will require control of many qubits in parallel, while performing error detection across the constituent qubits. Spin resonance techniques are a convenient path to parallel two-axis control, while Pauli spin blockade can be used to realize local parity measurements for error detection. Despite this, silicon qubit implementations have so far focused on either single-spin resonance control, or control and measurement via voltage-pulse detuning in the two-spin singlet-triplet basis, but not both simultaneously. Here, we demonstrate an integrated device platform incorporating a silicon metal-oxide-semiconductor double quantum dot that is capable of single-spin addressing and control via electron spin resonance, combined with high-fidelity spin readout in the singlet-triplet basis.Comment: 10 pages, 4 figure

Self-productivity and complementarities in human development : evidence from MARS

This paper investigates the role of self-productivity and home resources in capability formation from infancy to adolescence. In addition, we study the complementarities between basic cognitive, motor and noncognitive abilities and social as well as academic achievement. Our data are taken from the Mannheim Study of Children at Risk (MARS), an epidemiological cohort study following the long-term outcome of early risk factors. Results indicate that initial risk conditions cumulate and that differences in basic abilities increase during development. Self-productivity rises in the developmental process and complementarities are evident. Noncognitive abilities promote cognitive abilities and social achievement. There is remarkable stability in the distribution of the economic and socio-emotional home resources during the early life cycle. This is presumably a major reason for the evolution of inequality in human development