Van der Waals (vdW) materials have emerged over the last decade as the new playground for quantum photonics devices. Among them, hexagonal boron nitride (hBN) is an interesting candidate, mainly because of its crystallographic compatibility with many different 2D materials, but also because of its ability to host optically active defects. We have recently generated a first optically addressable spin defect (color center) in hBN with triplet ground state, which we have assigned to negatively charged boron vacancies (VB-). We have demonstrated the coherent control of VB- at room temperature and determined the relevant spin relaxation times. In this respect, sensors based on such color centers embedded in vdW heterostructures could be particularly attractive, since the distance between the sensor and the object to be sensed can be quite small. Finally, the influence of external stimuli such as magnetic field, temperature and pressure on this spin defect will also be discussed.
 A. Gottscholl, M. Kianinia, V. Soltamov, C. Bradac, C. Kasper, K. Krambrock, A. Sperlich, M. Toth, I. Aharonovich, and V. Dyakonov, Nature Mater. 19, 540 (2020)