Coupling spin defects in hexagonal boron nitride to a microwave cavity

Optically addressable spin defects in hexagonal boron nitride (hBN) have become a promising platform for quantum sensing. While sensitivity of these defects is limited by their interactions with the spin environment in hBN, inefficient microwave delivery can further reduce their sensitivity. Here, we design and fabricate a microwave double arc resonator for efficient transferring of the microwave field at 3.8 GHz. The spin transitions in the ground state of V-B(-) B are coupled to the frequency of the microwave cavity, which result in enhanced optically detected magnetic resonance (ODMR) contrast. In addition, the linewidth of the ODMR signal further reduces, achieving a magnetic field sensitivity as low as 42.4 mu T/root Hz. Our robust and scalable device engineering is promising for future employment of spin defects in hBN for quantum sensing.

Automated summary

By designing and fabricating a microwave double arc resonator, efficient transferring of the microwave field was achieved for optically addressable spin defects in hexagonal boron nitride (hBN), resulting in enhanced optically detected magnetic resonance (ODMR) contrast and low magnetic field sensitivity. This robust and scalable device engineering holds promise for future applications of spin defects in hBN for quantum sensing.