Imperial researchers including Paul Dichtl from CQD cohort 8 have managed to embed the nonlinear medium in a few-nanometre-sized gap where the light.

All-optical processing of information is an important research topic in photonics today, as it avoids losses incurred by having to convert the photons into an electronic signal and back into light. In order to achieve all-optical processing, photons must be made interact by sending them into a nonlinear medium, however, light has to travel very far in such a medium to reach an appreciable interaction. The Imperial team including Paul Dichtl from cohort 8 in the CDT for controlled quantum dynamics managed to embed the nonlinear medium in a few-nanometre-sized gap where the light intensity, and hence the nonlinear interaction, can be strongly enhanced. As a result, strong interaction of light was observed in only a few micrometres length of this gap, rather than several metres of optical fibre. This also allows for on-chip photon pair generation or frequency conversion of single-photon sources with potential applications in quantum optics. The publication is to be found in Science http://science.sciencemag.org/content/358/6367/1179