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.
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.
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.
Wide-field nitrogen-vacancy (NV) magnetic imaging at cryogenic temperatures requires microwave excitation and reliable knowledge of the temperature near the sensing region. Here, we report an integrated diamond quantum-sensing platform combining an ensemble of NV centers with a boron-doped diamond (BDD) microwave antenna and thermometer formed on the same diamond substrate. The BDD antenna provides microwave excitation for optically detected magnetic resonance measurements, and the BDD thermometer monitors the thermal environment near the NV sensing region. The BDD thermometer detected laser-induced local heating that was not clearly resolved by a stage-mounted thermometer. Using this platform, we imaged the temperature-dependent Meissner response of multiple cuprate superconductors while recording the temperature. These results demonstrate that the integrated BDD--NV platform provides a practical approach for cryogenic wide-field magnetic imaging with integrated microwave delivery and local thermometry.
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.
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.
Efficient collection of photoluminescence arising from spin dynamics of nitrogen vacancy (NV) centers in diamond is important for practical applications involving precise magnetic field or temperature mapping. These goals may be realized by the integration of nanodiamond particles with optical fibers and volumetric doping of the particles alongside the fiber core. That approach combines the advantages of robust axial fixation of NV diamonds with a direct spatial overlap of their fluorescence with the guided mode of the fiber. We developed a suspended core silicate glass fiber with 750 nm-diameter nanodiamonds located centrally in the 1.5 µm-core cross-section along its axis. The developed fiber probe was tested for its magnetic sensing performance in optically detected magnetic resonance measurements using a 24 cm-long fiber sample, with the NV excitation and fluorescence collection from the far ends of the sample and yielding optical readout contrast of 7% resulting in 0.5 µT·Hz-1/2 magnetic field sensitivity, two orders of magnitude better than in earlier designs. Thanks to its improved fluorescence confinement, the developed probe could find application in magnetic sensing over extended fiber length, magnetic field mapping or gradiometry.
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.