Researchers create scalable platform for on-chip quantum emitters

Household lightbulbs give off a chaotic torrent of energy, as trillions of miniscule light particles—called photons—reflect and scatter in all directions. Quantum light sources, on the other hand, are like light guns that fire single photons one by one, each time they are triggered, enabling them to carry hack-proof digital information—technology attractive to industries such as finance and defense.

Now, researchers at Stevens Institute of Technology and Columbia University have developed a scalable method for creating large numbers of these quantum light sources on a chip with unprecedented precision that not only could pave the way for the development of unbreakable cryptographic systems but also quantum computers that can perform complex calculations in seconds that would take normal computers years to finish.

"The search for scalable quantum light sources has been going on for 20 years, and more recently has become a national priority," says Stefan Strauf, who led the work and is also director of Stevens' Nanophotonic Lab. "This is the first time anyone has achieved a level of spatial control combined with high efficiency on a chip that is scalable, all of which are needed to realize quantum technologies."

The work, to be reported in the Oct. 29 advance online issue of Nature Nanotechnology, describes a new method for creating quantum light sources on demand in any desired location on a chip, by stretching an atom-thin film of semiconducting material over nanocubes made of gold. Like taut cling-wrap, the film stretches over the corners of the nanocubes, imprinting defined locations where single-photon emitters form.