Cambridge researchers have developed a new quantum sensor using hBN defects, surpassing current diamond-based technology by enabling multi-axis, high-resolution magnetic field detection at room temperature. (Artist’s concept.) Credit: SciTechDaily.com
Cambridge researchers created a quantum sensor using hBN, offering improved magnetic field detection over diamond-based sensors with new imaging possibilities.
A team of physicists at the University of Cambridge has achieved a major breakthrough in quantum sensing by showing that spin defects in hexagonal boron nitride (hBN) can serve as powerful sensors at room temperature. These sensors are capable of detecting magnetic fields at the nanoscale in multiple directions. The findings, published in Nature Communications, represent a key advance toward more practical and flexible quantum technologies.
“Quantum sensors allow us to detect nanoscale variations of various quantities. In the case of magnetometry, quantum sensors enable nanoscale visualization of properties like current flow and magnetization in materials leading to the discovery of new physics and functionality,” said Dr. Carmem Gilardoni, co-first author of this study at Cambrdge’s Cavendish Laboratory. “This work takes that capability to the next level using hBN, a material that’s not only compatible with nanoscale applications but also offers new degrees of freedom compared to state-of-the-art nanoscale quantum sensors.”
Advancing beyond diamond-based sensors
Until now, nanoscale quantum magnetometry at room temperature has only been possible using nitrogen vacancy (NV) center defects in diamond. Although effective, these sensors face limitations due to their underlying photophysics. Specifically, NV centers detect magnetic fields along a single axis and have a limited dynamic range. In contrast, the hBN-based sensor developed by the Cambridge team overcomes these challenges by enabling multi-axis magnetic field detection with a much broader dynamic range.
Artist’s impression of hexagonal boron nitride layers containing a spin, represented by the red arrow, which can be used for sensing magnetic fields. Credit: Carmem M. Gilardoni/ Simone Eizagirre Barker / Cavendish Laboratory
The researchers not only demonstrated the sensor’s capabilities but also uncovered the physical reasons behind its performance. They found that the sensor’s wide dynamic range and ability to detect vectorial magnetic fields stem from the low symmetry of the hBN defects and their favorable excited-state optical properties.
hBN’s potential as a quantum sensing material
hBN is a two-dimensional material, similar to graphene, that can be exfoliated to just a few atomic layers thick. Atomic-scale defects in the hBN lattice absorb and emit visible light in a way that is sensitive to local magnetic conditions, making it an ideal candidate for quantum sensing applications.
In this study, the team investigated the response of the hBN defect fluorescence to variations in magnetic field, using a technique known as optically detected magnetic resonance (ODMR). By carefully tracking the spin response and combining this with detailed analysis of the dynamics of photon emission, the team could uncover the underlying optical rates of the system and their connection to the defect symmetry, and how this combination results in a robust and versatile magnetic field sensor.
Unlocking new applications for quantum imaging
“ODMR isn’t a new technique – but what we have shown is that probes built using the hBN platform would allow this technique to be applied in a variety of new situations. It’s exciting because it opens the door to imaging magnetic phenomena and nanomaterials in a way we couldn’t before,” said Dr. Simone Eizagirre Barker, co-first author of the paper.
“This sensor could open the door to studying magnetic phenomena in new material systems, or with higher spatial resolution than has been done before,” said Prof Hannah Stern, who co-led the research with Prof Mete Atatüre at the Cavendish Laboratory. “The 2D nature of the host material also opens exciting new possibilities for using this sensor. For example, the spatial resolution for this technique is determined by the distance between the sample and sensor. With an atomically-thin material, we can potentially realize atomic-scale spatial mapping of magnetic field.”
Reference: “A single spin in hexagonal boron nitride for vectorial quantum magnetometry” by Carmem M. Gilardoni, Simone Eizagirre Barker, Catherine L. Curtin, Stephanie A. Fraser, Oliver. F. J. Powell, Dillon K. Lewis, Xiaoxi Deng, Andrew J. Ramsay, Sonachand Adhikari, Chi Li, Igor Aharonovich, Hark Hoe Tan, Mete Atatüre and Hannah L. Stern, 28 May 2025, Nature Communications.
