Scalable quantum technologies may be achieved by faithful conversion between matter qubits and photonic qubits in integrated circuit geometries. Within this context, quantum dots possess well-defined spin states (matter qubits), which couple efficiently to photons. By embedding them in nanophotonic waveguides, they provide a promising platform for quantum technology implementations. In this paper, we demonstrate that the naturally occurring electromagnetic field chirality that arises in nanobeam waveguides leads to unidirectional photon emission from quantum dot spin states, with resultant in-plane transfer of matter-qubit information. The chiral behaviour occurs despite the non-chiral geometry and material of the waveguides. Using dot registration techniques, we achieve a quantum emitter deterministically positioned at a chiral point and realize spin-path conversion by design. We further show that the chiral phenomena are much more tolerant to dot position than in standard photonic crystal waveguides, exhibit spin-path readout up to 95±5% and have potential to serve as the basis of spin-logic and network implementations.

No abstract

Todorokite of chemical composition (Mg(0.77)Na(0.03))(Mg(0.18)Mn(2+)(0.60)Mn(4+)(5.22)22) O(12).3.07 H(2)O was synthesized by a two-step procedure. First, sodium birnessite was synthesized and magnesium was exchanged for sodium to form magnesium birnessite, which was autoclaved under a saturated steam pressure at 155 degrees C for 8 hours to form well-crystallized todorokite. Synthesized todorokite particles consisted of fibers extending from a central plate. The plate itself was made of twinned fibers forming a trilling pattern. The infrared spectra and x-ray diffraction patterns were similar to those of natural todorokite samples. Calcium birnessite and nickel birnessite, when autoclaved under conditions similar to those for magnesium birnessite, yielded a todorokite structure. However, the formation of todorokite from calcium and nickel birnessite was less extensive.

Scanning electron microscopy and X‐ray microanalysis were employed to characterize the morphological properties of iron coatings on rice roots at different growth stages. This information is needed for further understanding of the influence of Fe coatings on rice plant development. Rice root coatings are visible about 1 week after flooding as a brownish discoloration which thickens with age of the root. No coating was found on younger parts of major roots near their tips or on young secondary roots which are critical regions of nutrient uptake. Roots of ‘Brazos’ cultivar rice (Oryza sativa L.) plants grown in Beaumont clay soil had a relatively thin coating of FeOOH mixed with soil particles before panicle differentiation. As a rice plant approached maturity and the outermost cell wall of the root decomposed, a mixture of FeOOH and soil particles began to fill the rectangular spaces that had once been occupied by epidermal cells. Casts in open cell cavities are porous and rough on the exterior side of the root. There were many shapes of casts and they generally matched the varied shapes of the outer layer of epidermal cells of rice roots. Roots of Brazos cultivar rice grown to maturity in Katy fine sandy loam soil have completely developed polyhedral casts. Precipitation of relatively pure FeOOH on cell walls formed hollow casts with the shapes of the original cells. The models presented describe hypothetical steps in the formation of the two types of casts observed by the oxidation of Fe2+ by O2 and precipitating of iron on the walls of closed and open cell cavities.

No abstract