Spin defects in hexagonal Boron Nitride (hBN) attract increasing interest for quantum technology since they represent optically-addressable qubits in a van der Waals material. In particular, negatively-charged boron vacancy centers (VB−) in hBN have shown promise as sensors of temperature, pressure, and static magnetic fields. However, the short spin coherence time of this defect currently limits its scope for quantum technology. Here, we apply dynamical decoupling techniques to suppress magnetic noise and extend the spin coherence time by nearly two orders of magnitude, approaching the fundamental T1 relaxation limit. Based on this improvement, we demonstrate advanced spin control and a set of quantum sensing protocols to detect electromagnetic signals in the MHz range with sub-Hz resolution. This work lays the foundation for nanoscale sensing using spin defects in an exfoliable material and opens a promising path to quantum sensors and quantum networks integrated into ultra-thin structures.
@article{arxiv.2212.12826,
title = {Extending the coherence time of spin defects in hBN enables advanced qubit control and quantum sensing},
author = {Roberto Rizzato and Martin Schalk and Stephan Mohr and Joachim P. Leibold and Jens C. Hermann and Fleming Bruckmaier and Peirui Ji and Georgy V. Astakhov and Ulrich Kentsch and Manfred Helm and Andreas V. Stier and Jonathan J. Finley and Dominik B. Bucher},
journal= {arXiv preprint arXiv:2212.12826},
year = {2022}
}