Abstract We demonstrate a method for thermal detection that is the sensitivity 6.2 mK Hz −1 2 , which uses the frequency lock closed-loop scheme to track Zeeman-split resonance of nitrogen-vacancy (NV) centers in diamond. The NV diamond surface acts as a temperature measurement sensor to transfer the temperature variation as D ( T ) parameter change to lead to the movement of the energy levels to detect the temperature. By frequency modulation technology and closed-loop feedback locking technology, automatic temperature detection and step signal reading are realized, with a resolution of 7.6 mK. It is found that the closed-loop output is basically unchanged, while the open-loop output has an error signal proportional to the laser fluctuation. The closed-loop feedback technique can improve the stability and resolution of the system and provides a method for measuring the actual temperature detection. Such a demonstration marks a vital advance in transitioning the NV thermometer from a laboratory system to a functional device for detecting temperature fields in a practical environment.
Abstract We demonstrate a method for thermal detection that is the sensitivity 6.2 mK Hz −1 2 , which uses the frequency lock closed-loop scheme to track Zeeman-split resonance of nitrogen-vacancy (NV) centers in diamond. The NV diamond surface acts as a temperature measurement sensor to transfer the temperature variation as D ( T ) parameter change to lead to the movement of the energy levels to detect the temperature. By frequency modulation technology and closed-loop feedback locking technology, automatic temperature detection and step signal reading are realized, with a resolution of 7.6 mK. It is found that the closed-loop output is basically unchanged, while the open-loop output has an error signal proportional to the laser fluctuation. The closed-loop feedback technique can improve the stability and resolution of the system and provides a method for measuring the actual temperature detection. Such a demonstration marks a vital advance in transitioning the NV thermometer from a laboratory system to a functional device for detecting temperature fields in a practical environment.
We demonstrate a robust, scale-factor-free vector magnetometer, which uses a closed-loop frequency-locking scheme to simultaneously track Zeeman-split resonance pairs of nitrogen-vacancy (NV) centers in diamond. This technique offers a three-orders-of-magnitude increase in dynamic range compared to open-loop methodologies; is robust against fluctuations in temperature, resonance linewidth, and contrast; and allows for simultaneous interrogation of multiple transition frequencies. By directly detecting the resonance frequencies of NV centers oriented along each of the diamond's four tetrahedral crystallographic axes, we perform full vector reconstruction of an applied magnetic field.
We presented a high-sensitivity temperature detection using an implanted single nitrogen-vacancy (NV) center array in diamond. The high-order thermal Carr-Purcell-Meiboom-Gill (TCPMG) method was performed on the implanted single NV center in diamond in a static magnetic field. We demonstrated that under small detunings for the two driving microwave frequencies, the oscillation frequency of the induced fluorescence of the NV center equals approximately the average of the detunings of the two driving fields. On the basis of the conclusion, the zero-field splitting D for the NV center and the corresponding temperature could be determined. The experiment showed that the coherence time for the high-order TCPMG was effectively extended, particularly up to 108 $\ensuremath{\mu}\mathrm{s}$ for TCPMG-8, about 14 times the value 7.7 $\ensuremath{\mu}\mathrm{s}$ for thermal Ramsey method. This coherence time corresponded to a thermal sensitivity of 10.1 mK/Hz1/2. We also detected the temperature distribution on the surface of a diamond chip in three different circumstances by using the implanted NV center array with the TCPMG-3 method. The experiment implies the feasibility of using implanted NV centers in high-quality diamonds to detect temperatures in biology, chemistry, materials science, and microelectronic systems with high sensitivity and nanoscale resolution.
In this paper, we propose a two-dimensional thermometer module based on the Nitrogen-Vacancy (NV) centers in diamonds. The thermometer integrates four modules on one Printed Circuit Board (PCB) including a laser module and a corresponding voltage regulator circuit, a microwave module, a focusing module, and an acquisition module, and it has a constructed area of 6.4cm2. In the process of integrating equipment, we made a signal amplifier module to improve the signal-to-noise ratio (SNR). Through the amplifier module, we realize a∼25-fold increase in the fluorescence, and it successfully improved the SNR by∼8.9-fold. Fixed Frequency Optical Detection of Magnetic Resonance (FF-ODMR) measures the relationship between temperature (T) and photoluminescence (PL) by scanning the temperature field at 2.84GHz. Which is the most direct display of the thermometer. We developed an algorithm for analyzing the thermometer sensitivity based on PL the SNR analysis. The thermometer temperature-field sensitivity of approximately19nk/Hz1/2.
Modern sensing applications increasingly require the simultaneous measurement of multiple physical parameters with high sensitivity. However, traditional sensors often suffer from cross-sensitivity to different variables, making it difficult to separate overlapping effects, such as those caused by temperature and magnetic fields, in complex environments. This challenge highlights the need for robust multiparametric sensors capable of independently and accurately monitoring diverse conditions in real time. In this context, nitrogen-vacancy (NV) centers in diamond present a promising solution. These atomic-scale defects can be optically initialized, manipulated, and read out via laser excitation using optically detected magnetic resonance (ODMR), and they can operate under ambient and harsh conditions. In this work, we demonstrate a simultaneous and internally cross-validated sensing platform capable of detecting both magnetic fields and temperature with a sensitivity of around 500 nT/Hz and 10 mK/Hz, respectively. Our method integrates ODMR, zero-phonon line spectral shifts, and linewidth broadening, each providing independent spectral signatures sensitive to distinct physical effects. This approach enhances measurement precision, enables internal consistency checks, and decouples intertwined phenomena such as temperature-induced variations in magnetization. The demonstrated technique significantly expands the functional capabilities of NV-based sensors, advancing their potential for high-precision metrology in complex environments.
Nitrogen-vacancy (N-V) centers in diamond are promising quantum sensors due to their ultralong coherence time under ambient conditions and multimodal sensing capability. N-V centers are strongly coupled to magnetic fields, leading to unprecedented sensitivity in magnetic field sensing. However, the coupling strengths between N-V centers and other crucial parameters, such as temperature and pressure, are not as strong as that of the magnetic field, resulting in a relative low sensitivity. A previous study showed that the temperature sensitivity of a diamond quantum sensor could be largely improved by magnetic criticality enhancement. Here, we propose and demonstrate a hybrid quantum thermometer composed of bulk diamond with ensemble N-V centers and a gadolinium magnetic flux concentrator. In addition to the magnetic criticality enhancement of gadolinium, our scheme leverages the magnetic flux concentration and ensemble N-V centers, achieving a temperature sensitivity of about 251.5nK/Hz. Near the critical point, the spin resonance to temperature $(\mathrm{\ensuremath{\partial}}{f}_{\ifmmode\pm\else\textpm\fi{}}/\mathrm{\ensuremath{\partial}}T)$ reached 57.3MHz/K under an external magnetic field of 1.213 G, which is about 774 times enhanced compared with that of bare N-V centers. The submicrokelvin temperature resolution of our hybrid thermometer can be used in the calibration of a reference point of temperature, integrated marine environmental surveys, laser-frequency stabilization, aerospace high-stability temperature-control systems, and many other practical applications on a macroscopic scale.
The nitrogen-vacancy center in diamond has been broadly applied in quantum sensing since it is sensitive to different physical quantities. Meanwhile, it is difficult to isolate disturbances from unwanted physical quantities in practical applications. Here, we present a fiber-based quantum thermometer by tracking the sharp-dip in the zero-field optically detected magnetic resonance spectrum in a high-density nitrogen-vacancy ensemble. Such a scheme can not only significantly isolate the magnetic field and microwave power drift but also improve the temperature sensitivity. Thanks to its simplicity and compatibility in implementation and robustness, this quantum thermometer is then applied to the surface temperature imaging of an electronic chip with a sensitivity of 18mK/Hz. It thus paves the way to high sensitive temperature measurements in ambiguous environments.