Abstract: A photonic element for a quantum information processing device contains a high-purity silicon layer. The high-purity silicon layer contains integrated rare-earth element (REE) dopants at a concentration of 1019 cm?3 or less. An optical transition between the lowest crystal field levels of the REE dopants integrated in the high-purity silicon layer exhibits a homogeneous linewidth of 1 MHz or less at a temperature of 4 K or less. A method for producing such a photonic element is also disclosed.

Abstract: A micro-fabricated device for controlling trapped ions includes a substrate. A structured electrode layer is disposed over the substrate. The structured electrode layer forms a plurality of electrodes of an ion trap configured to trap ions in a space above the structured electrode layer. The structured electrode layer is formed of a multilayer stack. The multilayer stack includes an electrically conductive smoothing layer having a planarized surface and an electrically conductive top layer disposed over the planarized surface of the smoothing layer. The top layer provides an exposed surface of the structured electrode layer, the exposed surface having a mean surface roughness equal to or less than Ra=5 nm.

Abstract: A photonic element for a quantum information processing device contains a high-purity silicon layer. The high-purity silicon layer contains integrated rare-earth element (REE) dopants at a concentration of 1019 cm?3 or less. An optical transition between the lowest crystal field levels of the REE dopants integrated in the high-purity silicon layer exhibits a homogeneous linewidth of 1 MHz or less at a temperature of 4 K or less. A method for producing such a photonic element is also disclosed.