A New Room-Temperature Quantum Emitter in High-Quality Hexagonal Boron Nitride.

Light emitters in wide band gap semiconductors are of great fundamental interest and have potential as optically addressable qubits. Here we describe the discovery of a new quantum emitter in high-quality hexagonal boron nitride (h-BN) with a sharp emission line at 435 nm. The emitters are activated and deactivated by electron beam irradiation and have the spectral and temporal characteristics of single-photon emitters (SPEs) weakly coupled to lattice vibrations. The emitters are conspicuously absent from commercially available h-BN and are only present in ultra-high-quality h-BN grown using a special high-pressure method. This suggests that these emitters originate from impurities or related defects specific to this unique synthetic route. We propose a charged defect state as the origin of this new SPE.