Researchers from the University of Illinois Urbana-Champaign have developed a chip-based device that can store photons for over one microsecond. This represents a significant advance for quantum information systems, where photons often need to be paused so that other quantum operations can catch up.
This research is published in Nano Letters.
Engineers have long sought ways to slow or store photons temporarily. Conventional optical methods, which extend the path of light using fibers and mirrors, cause photons to be absorbed by matter over long distances. Alternative approaches using atoms have proven difficult to integrate with scalable chip-based systems.
How the device works
The research team fabricated a nanoscale waveguide from thin-film lithium niobate, a material known for strong light confinement and low optical loss. They doped this material with erbium atoms, which have useful quantum properties. Using a tunable laser, they arranged the atoms into an atomic frequency comb, which is a pattern of evenly spaced frequency peaks. This comb structure allows the atoms to temporarily catch and hold incoming photons for controlled periods.
The device can store multiple photons at once while preserving quantum information with high fidelity. Unlike previous quantum memory devices that require specialized laboratory conditions, this platform was designed for commercial scalability and easy replication.
This advance matters because practical quantum computers and communication networks will need integrated memory components that can work on standard chips. The research team plans to improve the device by enhancing retrieval efficiency and testing different erbium isotopes that resist noise better.
“This is not a one-off bespoke device,” notes a press release. “Its promise is in its simplicity: we’ve taken something that can typically only be done in a highly specialized laboratory environment and recast it in a platform that can be made commercially at scale by people who don’t know anything about quantum optics.”