Irradiation-induced lattice defects in silicon carbide (SiC) have already exceeded their previous reputation as purely performance-inhibiting. With their remarkable quantum properties, such as long room-temperature spin coherence and the possibility of downscaling to single-photon source level, they have proven to be promising candidates for a multitude of quantum information applications. One of the most crucial parameters of any quantum system is how long its quantum coherence can be preserved. By using the pulsed optically detected magnetic resonance (ODMR) technique, we investigate the spin-lattice relaxation time (T1) and spin coherence time (T2) of silicon vacancies in 4H-SiC created by neutron, electron and proton irradiation in a broad range of fluences. We also examine the effect of irradiation energy and sample annealing. We establish a robustness of the T1 time against all types of irradiation and reveal a universal scaling of the T2 time with the emitter density. Our results can be used to optimize the coherence properties of silicon vacancy qubits in SiC for specific tasks. arXiv:1908.06829v1 [cond-mat.mtrl-sci]

A model is proposed to describe the field-assisted molten salt ion exchange of N a + with A g + in glass. It accounts for the buildup of space-charge zones and for the pseudo-mixed-alkali effect. Simulations in 1D proved to be consistent with experimental results. The 1D model has been expanded to 2D, making it suitable for simulating the fabrication of channel waveguides. Using a first-order approximation, a good agreement between the simulations and the experimental data can be achieved.

Asymmetric optical multimode splitters based on optical waveguides were fabricated in glass substrates using a field-assisted ion exchange process. Accompanying simulations, conducted to study the light propagation, revealed the possibility to realize asymmetric splitters based on waveguides with different width. In the exchange process, broad mask openings in the blocking layer are compared to those consisting of closely spaced parallel lines with various widths. The waveguide profiles of the resulting splitters were recorded and the optical losses and splitting ratios were determined for a wavelength of 850 nm. Additionally data transmission tests were conducted and showed the suitability of the splitters for a bandwidth of 28 GBit/s.

This erratum reports corrections for the original publication, Appl. Opt. 60, 6632 (2021)APOPAI0003-693510.1364/AO.427171.

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