Real-time three-dimensional magnetic mapping is now possible utilising negatively charged boron-vacancy centres in hexagonal boron nitride. Previously, obtaining magnetic images of micron-sized regions required integration times lasting hours; the process can now be completed within minutes utilising frequency tracking of electron spin resonance signals. This technique achieved shot-noise limited sensitivity of 54 microteslas per root Hertz and reduces acquisition times by at least one order of magnitude compared to conventional methods.

A quicker method for mapping minuscule magnetic fields has been devised using quantum sensors built from hexagonal boron nitride. Existing techniques required hours to create detailed images; this approach captures comparable data within minutes, offering sharply faster acquisition times. The advancement overcomes limitations in current technology by continuously monitoring changes in electron spin resonance frequencies and enables dynamic imaging of magnetic sources with improved speed and sensitivity.

A faster technique is available for mapping magnetic fields at incredibly small scales, utilising quantum sensors constructed from hexagonal boron nitride, a material similar to graphene but possessing unique properties that allow it to host colour centres useful for sensing. Current methods often require hours to generate detailed images of micron-sized regions; however, this approach completes comparable scans in mere minutes, representing a key leap forward in speed and sensitivity.

This innovation relies on continuously monitoring changes in electron spin resonance frequencies, which are like tuning a radio receiver to find a specific signal emitted by atoms when exposed to magnetism, allowing real-time tracking of these signals. The team achieved diffraction-limited resolution, akin to how blurry an image becomes with a poor camera lens, and measured magnetic field gradients of 3.6 microtesla per nanometre using their system.

Rapid real time vector magnetometry using nitrogen vacancy colour centres

Sensitivity reached 54 μT/√Hz, representing a substantial improvement over existing techniques that necessitate ten or more hours to generate comparable magnetic images. This breakthrough enables real-time three-dimensional mapping with diffraction-limited resolution previously unattainable due to low optical detection contrast. The frequency tracking approach continuously monitors electron spin resonance signals from negatively charged boron-vacancy (V^-_B) centres within hexagonal boron nitride, bypassing limitations imposed by lengthy integration times and enabling active imaging of micron-sized magnetic sources.

Abhishek Kumar, Kai Wang, and Ronen Adato successfully mapped the field pattern generated by a conical metallic tip in just minutes, demonstrating gradients up to 3.6 ±0.2 μT/nm. They also detected field rates reaching 6 mT/s. Complete field maps were recorded in minutes using this method; conventional techniques require over ten hours for comparable images.

Field gradients reached 3.6 ±0.2 μT/nm with dynamic field rates detected up to 6 mT/s utilising this system. Monitoring changes in resonant frequency proves an effective method for fast, minute-scale imaging, although current experiments rely on carefully prepared samples of neutron-irradiated hBN flakes which limits immediate scalability towards broader applications.

Current limitations regarding sample geometry and probe preparation

While offering a substantial leap in speed for mapping minuscule magnetic fields, reducing acquisition times from hours to mere minutes, the technique faces challenges when scaling beyond its present experimental setup. Three-dimensional imaging was demonstrated using specifically prepared conical metallic tips as test samples; however, adaptability to more complex geometries or irregularly shaped objects remains uncertain. It is important to acknowledge that current demonstrations depend upon these carefully crafted conical metallic tips, with direct application to irregular or complex samples presenting a significant challenge.

Nevertheless, the reduction in imaging time from hours to minutes represents an advance for nanoscale magnetic field mapping despite immediate geometrical limitations. Achieving shot-noise limited sensitivity of 54 microtesla per root Hertz alongside measuring field gradients up to 3.6 microtesla per nanometre demonstrates this system’s capability and opens questions regarding mapping more complex sample geometries than those conical metallic tips used here.

The researchers demonstrated real-time magnetic field monitoring using frequency tracking of electron spin resonance in negatively charged boron-vacancy centers within hexagonal boron nitride. The system achieved a sensitivity of 54 μT/√Hz and measured field gradients up to 3.6 μT/nm, detecting dynamic changes at rates as high as 6 mT/s. Further work will focus on adapting the technique beyond current limitations with carefully prepared samples towards more complex geometries.

👉 More information
🗞 Real-time ESR tracking for sub-micron 3D magnetic mapping with VB- quantum sensors in hexagonal boron nitride
✍️ Jefferson A. O. Galindo, Edwin D. C. Sanchez, Cecília L. A. V. Campos, Allison R. Pessoa, Hugo A. D. Correia, José D. M. de Lima, Klaus Krambrock, Leonardo de S. Menezes and Anderson M. Amaral
🧠 ArXiv: https://arxiv.org/abs/2608.20502

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