Photon-controlling film delivers quantum technology boost

Scientists at Los Alamos National Laboratory in New Mexico have developed a thin film that can control the release of photons and could have applications in quantum computing.

Made from tungsten and selenium, the two-dimensional material was synthesised using chemical vapour deposition with a multi-step, diffusion-mediated gas source. It can facilitate the emission of single photons of light, a capability essential for all-optical quantum computing and key distribution. Key distribution is a fundamental component of the high-level cybersecurity that quantum technologies promise.  

“Efficiently controlling certain thin-film materials so they emit single photons at precise locations—what’s known as deterministic quantum emission—paves the way for beyond-lab-scale quantum materials,” said Michael Pettes, a Los Alamos National Laboratory materials scientist and leader of the multi-institution research team.

Described in the journal Applied Physics Letters, the research exploits strain at highly spatially localised and well-separated emission sites, or tips, in the tungsten/selenium film. The material’s ultra-thin profile means it conforms to the radius of the tips and bends slightly towards the substrate by a few per cent, like draping a sheet across a bed of nails. The resulting strain is enough to change the electronic structure at the tips, with the affected area emitting light of a different colour and nature than light from the rest of the film.