Purification of single-photon emission from hBN using post-processing treatments

Single-photon emitters (SPEs) in hexagonal boron nitride (hBN) are promising components for on-chip quantum information processing. Recently, large-area hBN films prepared by chemical vapor deposition (CVD) were found to host uniform, high densities of SPEs. However, the purity of these emitters has, to date, been low, hindering their applications in practical devices. In this work, we present two methods for postgrowth processing of hBN, which significantly improve SPEs in hBN films that had been transferred from substrates used for CVD. The emitters exhibit high photon purities in excess of 90% and narrow linewidths of similar to 3 nm at room temperature. Our work lays a foundation for producing high-quality emitters in an ultra-compact two-dimensional material system and paves the way for deployment of hBN SPEs in scalable on-chip photonic and quantum devices.