Coherent dynamics of strongly interacting electronic spin defects in hexagonal boron nitride.

ABSTRACT

Optically active spin defects in van der Waals materials are promising platforms for modern quantum technologies. Here we investigate the coherent dynamics of strongly interacting ensembles of negatively charged boron-vacancy ([Formula see text]) centers in hexagonal boron nitride (hBN) with varying defect density. By employing advanced dynamical decoupling sequences to selectively isolate different dephasing sources, we observe more than 5-fold improvement in the measured coherence times across all hBN samples. Crucially, we identify that the many-body interaction within the [Formula see text] ensemble plays a substantial role in the coherent dynamics, which is then used to directly estimate the concentration of [Formula see text]. We find that at high ion implantation dosage, only a small portion of the created boron vacancy defects are in the desired negatively charged state. Finally, we investigate the spin response of [Formula see text] to the local charged defects induced electric field signals, and estimate its ground state transverse electric field susceptibility. Our results provide new insights on the spin and charge properties of [Formula see text], which are important for future use of defects in hBN as quantum sensors and simulators.