All-optical nanoscale thermometry with silicon-vacancy centers in diamond

We demonstrate an all-optical thermometer based on an ensemble of silicon-vacancy centers (SiVs) in diamond by utilizing a temperature dependent shift of the SiV optical zero-phonon line transition frequency, $\mathrm{\Delta }\lambda \mathrm{/}\mathrm{\Delta }T=6.8\mathrm{G}\mathrm{H}\mathrm{z}\mathrm{/}\mathrm{K}$. Using SiVs in bulk diamond, we achieve $70\mathrm{m}\mathrm{K}$ precision at room temperature with a sensitivity of $360\mathrm{m}\mathrm{K}\mathrm{/}\sqrt{\mathrm{H}\mathrm{z}}$. Finally, we use SiVs in $200\mathrm{n}\mathrm{m}$ nanodiamonds as local temperature probes with $521\mathrm{m}\mathrm{K}\mathrm{/}\sqrt{\mathrm{H}\mathrm{z}}$ sensitivity. These results open up new possibilities for nanoscale thermometry in biology, chemistry, and physics, paving the way for control of complex nanoscale systems.