Boron nitride nanotubes (BNNTs) work as room-temperature single-photon emitters across the entire visible spectrum, including spectral regions where such emitters had not been reported in hexagonal boron nitride (hBN). A characterization using confocal photoluminescence and Hanbury Brown-Twiss interferometry opens a more compact route to integrating quantum sources into photonic circuits.

Quantum information systems, from quantum key distribution to quantum communications, require bright, stable, high-purity single-photon sources. Two-dimensional hBN flakes have been the most studied host material for these emitters, but working in two dimensions adds engineering complexity when coupling them to waveguides and other components. Reducing dimensionality through nanotubes promises to simplify that integration.

Each nanotube was found to host multiple single-photon emitters along its length, at varying emission wavelengths, with lifetimes as fast as 0.5 ns, about two-fold faster than the fastest known hBN emitters. In addition, surface passivation or coating mitigates blinking events and increases emitter stability.

The practical consequence is that a single nanotube, with a radius of only ~25 nm, can support several multiwavelength single-photon sources. That compact size eases deterministic placement within nanophotonic devices such as waveguides and interferometric filters, a relevant step toward integrated quantum photonic circuits.