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 the sensitivity of the zero-phonon line wavelength to temperature, Δ λ / Δ T = 0.0124 ( 2 ) nm K^–1 [6.8(1) GHz K^–1]. Using SiVs in bulk diamond, we achieve 70 mK precision at room temperature with a temperature uncertainty σ T = 360 mK / H z . Finally, we use SiVs in 200 nm nanodiamonds as local temperature probes with 521 mK/ H z uncertainty and achieve sub-Kelvin precision. These properties deviate by less than 1% between nanodiamonds, enabling calibration-free thermometry for sensing and control of complex nanoscale systems. [ABSTRACT FROM AUTHOR]