By analyzing the emission properties of individual G centers, we show that their motion dynamics is strongly sensitive to perturbations in the crystal environment. Especially, the silicon-on-insulator structure commonly used in microelectronics and nanophotonics induces a strain acting on the defects. As a consequence, the mobile atom of the G center, which is perfectly delocalized between 6 sites in the unperturbed case, jumps randomly between the different positions under optical excitation, like a ball in a 6-slot roulette wheel. By combining spectral and polarization analysis, we can link the G center emission lines to specific crystal sites.

The next challenge is to control the reconfiguration dynamics of single G centers in silicon. Exploration paths include strain engineering and the development of resonant excitation protocols to lock the mobile atom at a specific crystal site. Another promising research direction is to investigate how the atomic reconfiguration of the G center influences its spin quantum degree of freedom.​