Hybrid GaAs/AlGaAs nanowire --- quantum dot system for single photon sources

III–V nanowires, or a combination of the nanowires with quantum dots, are promising building blocks for future optoelectronic devices, in particular, single-photon emitters, lasers and photodetectors. In this work we present results of molecular beam epitaxial growth of combined nanostructures containing GaAs quantum dots inside AlGaAs nanowires on a silicon substrate showing a new way to combine quantum devices with Si technology.

RECORDS THEORY

In quantum gravity, one seeks to combine quantum mechanics and general relativity. In attempting to do so, one comes across the "problem of time" impasse: the notion of time is conceptually different in each of these theories. In this paper, I consider the timeless records approach to resolving this. Records are localized, information-containing subconfigurations of a single instant. Records theory is the study of these and of how science (or history) is to be abstracted from correlations between them. I critically evaluate motivations for this approach that have previously appeared in the literature. I provide a ground-level structure for records theory and discuss what kind of further tools are needed, illustrated with some toy models: ordinary mechanics, relational particle dynamics, detector models and inhomogeneous perturbations about homogeneous cosmology.