# Ultrasensitive all-optical thermometry using nanodiamonds with high concentration of silicon-vacancy centres and multiparametric data analysis

## TL;DR

This paper introduces ultrafast, highly sensitive all-optical nanodiamond thermometers with silicon-vacancy centers, capable of detecting minute temperature changes at nanoscale with unprecedented speed and precision, suitable for biological and electronic applications.

## Contribution

The study presents a novel thermometry method using high-concentration SiV centres in nanodiamonds combined with multiparametric photoluminescence analysis, achieving record readout speed and sensitivity.

## Key findings

- Achieved an intrinsic noise floor of about 10 mK/Hz^{1/2}.
- Demonstrated detection of 0.4°C temperature changes in 1 ms.
- Enhanced readout speed by a thousand-fold compared to existing methods.

## Abstract

Nanoscale thermometry is paramount to study primary processes of heat transfer in solids and is a subject of hot debate in cell biology. Here we report ultrafast temperature sensing using all-optical thermometry exploiting synthetic nanodiamonds with silicon-vacancy (SiV) centres embedded at a high concentration. Using multi-parametric analysis of photoluminescence (PL) of these centres, we have achieved an intrinsic noise floor of about 10 mK Hz$^{-1/2}$, which is a thousand-fold increase in the readout speed in comparison to the current record values demonstrated with all-optical methods of comparable spatial-resolution and precision. Our thermometers are smaller than 250-nm across but can detect a 0.4$^\circ$C change of temperature in a measurement taking only 0.001 second. The exceptional sensitivity and simplicity of these thermometers enable a wide range of applications such as temperature monitoring and mapping within intracellular regions and in state-of-the-art solid-state electronic nanodevices.