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, $Deltalambda/Delta T= 6.8,mathrm{GHz/K}$. Using SiVs in bulk diamond, we achieve $70,mathrm{mK}$ precision at room temperature with a sensitivity of $360,mathrm{mK/sqrt{Hz}}$. Finally, we use SiVs in $200,mathrm{nm}$ nanodiamonds as local temperature probes with $521,mathrm{ mK/sqrt{Hz}}$ sensitivity. These results open up new possibilities for nanoscale thermometry in biology, chemistry, and physics, paving the way for control of complex nanoscale systems.