Scientific Reports 7: Article number: 44813; published online: 20 March 2017; updated: 20 September 2017.

The original version of this Article contained typographical errors in the Abstract.

“Whispering Gallery Mode (WGM) analysis revealed large Quality Factors of order 2 × 106 (dielectric loss ~5 × 10−7) at high powers, degrading to 7 × 10−5 (dielectric loss ~1.4 × 10−6 at single photon energy. A very low-loss narrow line width paramagnetic spin flip transition was detected with extreme sensitivity in 28Si, with very small concentration below 1010 cm−3 (less than 10 parts per trillion) and g-factor of 1.995 ± 0.008”.

now reads:

“Whispering Gallery Mode (WGM) analysis revealed large Quality Factors of order 2 × 106 (dielectric loss ~5 × 10−7) at high powers, degrading to 7 × 105 (dielectric loss ~1.4 × 10−6) at single photon energy. A very low-loss narrow line width paramagnetic spin flip transition was detected with extreme sensitivity in 28Si, with very small concentration below 1011 cm−3 (less than 10 parts per trillion) and g-factor of 1.995 ± 0.008”.

This has now been corrected in the PDF and HTML versions of the Article.