Graphene Flagship researchers from the University of Cambridge have created large scale arrays of quantum emitters in different transition metal dichalcogenides (TMDs). The work could lead to large quantities of on demand, single photon emitters, in turn paving the way for integrating such features in electronic devices, creating hybrid on-chip photonics devices for networks and sensing applications.

According to the team, quantum light emitters – or quantum dots – are of interest for many applications. However, it has been difficult to produce large arrays of quantum emitters close together while maintaining high quality. “It’s almost a Goldilocks problem –one either obtains good single photon sources or good arrays, but not both at the same time,” said Professor Mete Atatüre from the Cavendish Laboratory. “Now, all of a sudden, we can have hundreds of these emitters in one sample.”

TMDs are layered semiconductors that can be exfoliated into layers only a few atoms thick. Recent research has shown that some TMDs can emit single photons. But, until now, the occurrence of these quantum light emitters has been random.

This random nature made systematic investigation difficult, but the team is now able to take a deterministic approach. “The ability to create our sources deterministically has made a dramatic change,” Prof Atatüre continued. “Previously it was pure luck. Now, we can do research in a more systematic way.”

To create the quantum light sources, the researchers cut an array of nanoscale pillars into silica or nanodiamond, then suspended the TMD layer on top of the pillars. Quantum emitters are created in the TMD where it is supported by the pillars, so it is possible to choose exactly where the single photons should be generated.

Professor Andrea Ferrari, chair of the Graphene Flagship’s Management Panel, added: ”It is great to see that layered materials have now a firm place amongst the promising approaches for generation and manipulation of quantum light and could be enablers of a future integrated technology.”