Quantum LED heralds computing advance

Ultra-thin quantum LEDs have been developed by researchers at the University of Cambridge that can produce single photons – making them important in building quantum network on compact chips.

Made of layered graphene, boron nitride and transition metal dichalcogenides (TMDS), the LEDs measure a few atoms thick. As they can produce single photons, their potential future use includes on-chip photon sources in quantum computing.

Professor Andrea Ferrari, director of the Cambridge Graphene Centre and one of the co-authors, said: “We are just scratching the surface of the many possible applications of devices prepared by combining graphene with other materials. In this case, not only have we demonstrated controllable photon sources, but we have also shown the field of quantum technologies can greatly benefit from layered materials. Many more exciting results and applications will surely follow.”

The TMD layer of the LED contains regions where electrons and electron vacancies are tightly confined. When an electron fills a vacancy at a lower energy level than the electron, the energy difference is released as a photon. The researchers say what they have created provides high levels of tunability, integration capabilities and design freedom.

Quantum computing promises increased power and security over current digital computing, but it cannot be created until reliable methods to generate single, indistinguishable photons have been established.

Professor Mete Atatüre of Cambridge’s Cavendish Laboratory, one of the paper’s senior authors, said: “For quantum communication with single photons, and quantum networks between different nodes, we want to be able to just drive current and get light out. There are many emitters that are optically excitable, but only a handful are electrically driven.”

Quantum emitters have also been seen in another TMD material – tungsten disulphide (WS₂). The scientists hope other layered materials could have quantum dot-like features also. The research was published in Nature Communications.