  Single photon emitters (SPEs) in low-dimensional layered materials have
recently gained a large interest owing to the auspicious perspectives of
integration and extreme miniaturization offered by this class of materials.
However, accurate control of both the spatial location and the emission
wavelength of the quantum emitters is essentially lacking to date, thus
hindering further technological steps towards scalable quantum photonic
devices. Here, we evidence SPEs in high purity synthetic hexagonal boron
nitride (hBN) that can be activated by an electron beam at chosen locations.
SPE ensembles are generated with a spatial accuracy better than the cubed
emission wavelength, thus opening the way to integration in optical
microstructures. Stable and bright single photon emission is subsequently
observed in the visible range up to room temperature upon non-resonant laser
excitation. Moreover, the low-temperature emission wavelength is reproducible,
with an ensemble distribution of width 3 meV, a statistical dispersion that is
more than one order of magnitude lower than the narrowest wavelength spreads
obtained in epitaxial hBN samples. Our findings constitute an essential step
towards the realization of top-down integrated devices based on identical
quantum emitters in 2D materials.
