Single photons sources (SPS) play a central role in the experimental foundation of quantum computing. Currently, there is a large scientific effort in identifying new bright and stable single-photon emission sources, with the aim of extending the spectral range achievable by quantum emitters. In the last years low dimensional layered semiconductors appeared as new promising optical materials and low energy SPS have been identified in transition metal dichalcogenides. In this work, thanks to a newly developed optical set-up integrated in a scanning transmission electron microscope, we have identified a new very bright UV single photon emitter in hexagonal boron nitride. Read more »