Vectorial quantum magnetometry
"This sensor could open the door to studying the magnetic phenomena in new materials systems, or with higher spatial resolution than has been done before".
Professor Hannah Stern
Professor Hannah Stern co-led a team at the University of Cambridge, who have made a breakthrough in quantum sensing by demonstrating the use of spin defects in Hexagonal Boron Nitride (hBN) as powerful, room-temperature sensors capable of detecting vectorial field at the nanoscale. The findings mark a significant step toward more practical and versatile quantum technologies.
The work demonstrates the next level using hBM, being a material that is compatible with nanoscale applications and which also offers new degrees of freedom when compared to state-of-the-art nanoscale quantum sensors (which need the nitrogen vacancy centre defect in diamond). In contrast, the hBN sensor development by Professor Stern's team does not share these limitations, and instead presents a multi-axis sensor of magnetic field with a large dynamic range.
The team's work provides a mechanistic understanding of the origin of its advantageous properties for sensing. Importantly, the team uncovered that the low symmetry, and fortuitous excited state optical rates, are responsible for the dynamic range and vectorial capabilities.
hBN is a two-dimensional material, similar to graphene, that can be exfoliated to just a few atomic 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 paper* the team investigated the response of the hBN defect fluoresence to variations in magnetic field, using the optically detected magnetic resonance (ODMR) technique. By carefully tracking the spin response and combining this with details analysis of the dynamics of photon emission, the team could uncover the underlying optical rate system and their connection to the defect symmetry, and how this combination resulted in a robust and versatile magnetic field sensor.
As Professor Stern says:
The 2D nature of the host materials 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 the sensor. With an atomically-thin material we can potentially realise atomic scale spatial mapping of magnetic field".
* A single spin in hexagonal boron nitride for vectorial quantum magnetometry' published in Nature Communications.
