Temperature Sensing with RF-Dressed States of Nitrogen-Vacancy Centers in Diamond

TL;DR

This paper introduces a novel RF-dressed state method for NV center-based temperature sensing using CW-ODMR, significantly improving sensitivity and reducing inhomogeneous broadening.

Contribution

The authors develop a new RF-dressed CW-ODMR technique that enhances temperature sensitivity and mitigates strain-induced broadening in NV centers.

Findings

Linewidth narrows with RF dressing compared to conventional methods.

Sensitivity improves by approximately seven times, reaching 65.5 mK/√Hz.

Experimental validation confirms the effectiveness of the RF-dressed scheme.

Abstract

Nitrogen vacancy (NV) centers in diamond are promising systems for realizing sensitive temperature sensors. Pulsed optically detected magnetic resonance (Pulsed-ODMR) is one of the ways to measure the temperature using NV centers. However, Pulsed-ODMR requires careful calibration and strict time synchronization to control the microwave pulse, which complicates its applicability. Nonetheless, the continuous-wave optically detected magnetic resonance (CW- ODMR) in NV centers is another more advantageous way to measure temperature with NV centers, owing to its simple implementation by applying a green laser and microwave in a continuous manner. This, however, has the drawback of a lower sensitivity compared to pulsed-ODMR. Therefore, to benefit from its accessible adaptation, it is highly important to improve the sensitivity of temperature sensing with CW-ODMR. Here, we propose a novel method to measure temperature using CW-ODMR with a quantum state dressed by radio-frequency (RF) fields under transverse magnetic fields. RF fields are expected to suppress inhomogeneous broadening owing to strain variations. Experimental results confirmed that the linewidth becomes narrower in our scheme compared to the conventional one. Moreover, we estimated the sensitivity to be approximately 65.5 $\mathrm{m}\mathrm{K}/\sqrt{\mathrm{Hz}}$, which constitutes approximately seven times improvement with respect to the sensitivity of the conventional scheme.