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 10.sup.19 cm.sup.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.